From the Mountains to the Ocean - · PDF fileGERSTEL BRASIL +55 11 5665 8931 [email protected] GERSTEL GmbH & Co KG Mülheim an der Ruhr, Eberhard-Gerstel-Platz 1 45473 Mülheim

News from GERSTEL GmbH & Co. KG · Eberhard-Gerstel-Platz 1 · 45473 Mülheim an der Ruhr · Germany · Phone + 49 (0) 2 08 - 7 65 03-0 · [email protected] ww

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G L O B A L A N A L Y T I C A L S O L U T I O N S

Ultratrace Analysis with the GERSTEL-

From the Mountains to the Ocean

www.gerstel.com

GERSTEL, Inc., USA +1 410 - 247 5885 [email protected]

GERSTEL K.K., Japan +81 3 57 31 53 21 [email protected]

GERSTEL LLP, Singapore +65 6622 5486 [email protected]

GERSTEL GmbH & Co. KG,Germany +49 208 - 7 65 03-0 [email protected]

GERSTEL AG, Switzerland +41 41 - 9 21 97 23 [email protected]


Subject to change. GERSTEL®, GRAPHPACK® and TWISTER® are registered trademarks of GERSTEL GmbH & Co. KG.Printed in Germany · 0210 · © Copyright by GERSTEL GmbH & Co. KG

GERSTEL BRASIL +55 11 5665 8931 [email protected]

GERSTEL GmbH & Co KGMülheim an der Ruhr, Eberhard-Gerstel-Platz 1 45473 Mülheim an der RuhrGermany

+49 (0)208 - 7 65 03 0 +49 (0)208 - 7 65 03 33 gerstel @gerstel.com http://www.gerstel.com

GERSTEL, Inc.701 Digital DriveSuite JLinthicum, MD 21090USA

+1 410 - 247 5885 +1 410 -247 5887 [email protected] http://www.gerstelus.com

GERSTEL K. K.2-13-18 Nakane, Meguro-ku152-0031 TokyoDai-Hyaku Seimei ToritsudaiEkimae Bldg 2FJapan

+ 81 3 5731 5321 + 81 3 5731 5322 [email protected] http://www.gerstel.co.jp

GERSTEL LLPLevel 25, North TowerOne Raffles QuaySingapore 048583

+65 6622 5486 +65 6622 5999 [email protected]

GERSTEL AGWassergrabe 276210 SurseeSwitzerland

+41 (0)41 - 9 21 97 23 +41 (0)41 - 9 21 97 25 [email protected]

Our service and support network: Distributors in the following countries. For countries not listed please contact [email protected].

Armenia, Argentina, Australia, Austria, Bahrain, Belgium, Belorussia, Botswana, Brasil, Cambodia, Canada, China, CyprusvDenmark, Egypt, Estonia, Finland, France, Geor-gia, Greece, Hungary, Iceland, India, Indonesia, Israel, Italy, Japan, Jordan, Korea, Kuwait, Laos, Lesotho, Latvia, Luxembourg, Malaysia, Mexico, Mongolia, Myanmar, Namibia, Netherlands, New Zealand, Norway, Poland, Portugal, Qatar, Romania, Russia, Singapore, Slovak Republic, Slovenia, South Africa, Spain, Swaziland, Sweden, Switzerland, Taiwan, Thailand, Turkey, Ukraina, United Arab Emirates, United Kingdom, USA, Vietnam, Zimbabwe

GERSTEL world-wide

GERSTELMultiPurposeSamplerMPS

This is what the new MPS

offers you:

MultiPurpose SamplerMPS

GERSTEL MultiPurpose Sampler MPSHighly productive automated sample preparation and sample introduction for GC/MS und LC/MS

GERSTEL MPS• Proven and reliable technologyThe GERSTEL MPS has proven its worth in industry, contract laboratories, public safety departments, and in academia world-wide. The MPS provides highly efficient automated sample preparation and sample introduction for GC/MS and LC/MS.

• Best possible productivityThanks to intelligent synchronization, sample preparation and chromatography are performed in pa-rallel. Whenever your analysis system is ready, the next sample is prepared and ready to be injected. This ensures that your analysis system is never idle, always utilized to its full capacity for best possible productivity.

• Intuitive operationThe GERSTEL MAESTRO software lets you operate your MPS by mouse-click whether it is operated independently or integrated with the analysis system. MAESTRO operates fully integrated with the Agilent ChemStation or GC MassHunter. One method and one sequence table control the complete system from sample preparationto GC/MS or LC/MS analysis. MAESTRO operates integrated with the sequence tables of Agilent LC MassHunter, AB Sciex Analyst®- and ThermoFisher Scientific XCalibur.

• Maximum fl exibilityThe MPS lets you automate a wide range of standard or special sample preparation technologies. Whenever it is needed, the MPS easily and quickly adapts to the task at hand.

THE NEW

Versatile autosampler and sample preparation robot for your analytical lab

Modern laboratory processes frequently offer significant potential for improve-ments in the fields of sample preparation and -introduction. Improving productivity and performance while cutting per sample cost is realistic provided you have cho-sen an autosampler that rises to the task and can be adapted to meet new challen-ges as demands change. The GERSTEL MultiPurpose Sampler MPS enables highly efficient automation of sample preparation and sample introduction for GC/MS and LC/MS. Or you can use the MPS as WorkStation independent of the analysis systems, providing prepared samples for multiple techniques in the lab. Whichever MPS you choose, you are sure to get reliable results and increased throughput combined with the flexibility to adapt effortlessly to changes and new challenges.

The MPS is not just an attractive addition to your lab:1. Routine tasks are performed reliably - every day.2. Your analytical instrument is utilized to full capacity, sample preparation and analysis are performed in parallel and synchronized for optimum throughput. 3. Set up your daily analysis sequence or add priority

samples with a few mouse-clicks using the intelligent MAESTRO software.4. MAESTRO works fully integrated with the Agilent ChemStation and GC/MS MassHunter and integrated with the Agilent LC/MS MassHunter, AB Sciex Analyst® and ThermoScienti� c XCalibur sequence tables.Your benefi t:

5. Your entire analysis from sample preparation to GC/MS or LC/MS analysis is controlled from one software platform, fully integrated or, in some cases, using one integrated sequence table.

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Versatile autosampler and sample preparation robot

This is what the new MPS

offers you:

Effi cient, produktive, reliableThe GERSTEL MultiPurpose Sampler MPS performs your routine analysis tasks efficiently and reliably. You benefit from the rugged and proven technology. To operate the system, method and sequence generation requires very limited training and no programming knowledge whatsoever. In almost no time, using only a few mouse-clicks, you have set up the system for preparation and analysis of your daily sample load – or for the weekend batch. And if you need to add priority samples when the system is running – no problem! Without stopping the ongoing analysis, you simply insert the priority sample into the sequence table and specify its position: As soon as the system has finished the ongoing analysis, the priority sample will jump the queue and be processed.

Flexible through and throughYou can handle almost any application challenge with the MPS. The modular concept enables you to react flexibly to new analytical demands. New sample preparation me-thods are quickly and easily generated using the MAESTRO PrepBuilder, available sample preparation options are easily activated or deactivated in the method and set-up, enabling you to react fast to newly arrived samples and to demands for new analysis methods. The MPS can be integrated into your analysis system combining sample preparation with sample introduction to your GC/MS or LC/MS – or it can be operated independently as a WorkStation, preparing samples for multiple analytical systems in the lab.

R&D: In the field of research and de-velopment, analysts benefit from the modular concept of the MPS, which enables fast and simple adaptation to constantly changing requirements and to new challenges. A wide range of sample preparation modules and tech-nologies are available from GERSTEL. You can easily and conveniently elimi-nate matrix residue from your sample or extract, add internal standards or deriva-tization reagent to improve the quality and limits of determination of your analysis – or change the solvent as needed to enable GC or HPLC analysis. Different sample preparation steps are combined easily and conveniently by mouse-click.

Routine analysis: Laboratory work is not routine until you can perform it wit-hout paying too much attention. Uncom-plicated and reliable operation combined with results you can trust and safely report to your clients – those are attributes of laboratory set-ups that are based on the GERSTEL MPS. The MPS has a proven record of providing first class sample preparation and sample introduction for GC/MS and LC/MS. The MPS can be com-bined with any standard chromatography system, the intelligent MAESTRO software control will help ensure that the combined system is utilized to its fullest capacity providing best possible productivity and throughput. You set up the sequence table for the day or for the weekend; the MPS takes care of the rest.

Benefi ts for R&D and routine analysis

No. 11

MultiPurpose SamplerMPSTHE NEW

Centerfold

FOOD SAFETY · FLAVOR PROFILING · WHISKEY AND WINE · ENVIRONMENTAL

GERSTEL Solutions worldwide No. 11

INNOVATIONThe new MPS: Driving productivity . . . . . . . . . . . . . . . . . . . . . page 3

Novel automated Pyrolyzer for the GERSTEL TDU . . . . . . . . . . page 24

ENVIRONMENTALPOP traces in icy heights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 4

FOOD SAFETYPolyaromatic seafood platter? . . . . . . . . . . . . . . . . . . . . . . . . . . page 7

Pesticides: So long, troublemakers I (GC-MS/MS) . . . . . . . . page 19

Pesticides: So long, troublemakers II (LC-MS/MS) . . . . . . . . . page 22

OFF-FLAVORSWine: Efficient and sensitive determination of TCA

and other off-flavors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 9

FLAVOR PROFILINGBeverages: Put on the 1D/2D goggles . . . . . . . . . . . . . . . . . . . page 13

Whiskey: See the big picture – and every little detail . . . . . . . . page 16

NEWSGERSTEL on expansion course in South East Asia . . . . . . . . . . page 12

Multi-Desorption Mode TD . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 12

THE NEW MPS – Centerfold

www.gerstel.com




GERSTEL GmbH & Co. KG,Germany +49 208 - 7 65 03-0

[email protected] AG, Switzerland +41 41 - 9 21 97 23 [email protected]


Subject to change. GERSTEL®, GRAPHPACK® and TWISTER® are registered trademarks of GERSTEL GmbH & Co. KG.

Printed in Germany · 0210 · © Copyright by GERSTEL GmbH & Co. KG


GERSTEL GmbH & Co KGMülheim an der Ruhr, Eberhard-Gerstel-Platz 1 45473 Mülheim an der RuhrGermany +49 (0)208 - 7 65 03 0 +49 (0)208 - 7 65 03 33 gerstel @gerstel.com http://www.gerstel.comGERSTEL, Inc.701 Digital DriveSuite J

Linthicum, MD 21090USA +1 410 - 247 5885 +1 410 -247 5887 [email protected] http://www.gerstelus.comGERSTEL K. K.2-13-18 Nakane, Meguro-ku

152-0031 TokyoDai-Hyaku Seimei ToritsudaiEkimae Bldg 2FJapan

+ 81 3 5731 5321 + 81 3 5731 5322 [email protected] http://www.gerstel.co.jpGERSTEL LLPLevel 25, North TowerOne Raffles QuaySingapore 048583 +65 6622 5486 +65 6622 5999 [email protected] AGWassergrabe 276210 SurseeSwitzerland +41 (0)41 - 9 21 97 23 +41 (0)41 - 9 21 97 25 [email protected] service and support network: Distributors in the

following countries. For countries not listed please

contact [email protected], Argentina, Australia, Austria, Bahrain, Belgium,

Belorussia, Botswana, Brasil, Cambodia, Canada, China,

CyprusvDenmark, Egypt, Estonia, Finland, France, Geor-

gia, Greece, Hungary, Iceland, India, Indonesia, Israel,

Italy, Japan, Jordan, Korea, Kuwait, Laos, Lesotho, Latvia,

Luxembourg, Malaysia, Mexico, Mongolia, Myanmar,

Namibia, Netherlands, New Zealand, Norway, Poland,

Portugal, Qatar, Romania, Russia, Singapore, Slovak

Republic, Slovenia, South Africa, Spain, Swaziland,

Sweden, Switzerland, Taiwan, Thailand, Turkey, Ukraina,

United Arab Emirates, United Kingdom, USA, Vietnam,

Zimbabwe

GERSTEL world-wide

GERSTELMultiPurposeSamplerMPS

This is what the new MPS offers you:

MultiPurpose SamplerMPS

GERSTEL MultiPurpose Sampler MPS

Highly productive automated sample preparation and

sample introduction for GC/MS und LC/MSGERSTEL MPS• Proven and reliable technologyThe GERSTEL MPS has proven its worth in industry, contract laboratories, public safety departments,

and in academia world-wide. The MPS provides highly efficient automated sample preparation and

sample introduction for GC/MS and LC/MS.• Best possible productivityThanks to intelligent synchronization, sample preparation and chromatography are performed in pa-

rallel. Whenever your analysis system is ready, the next sample is prepared and ready to be injected.

This ensures that your analysis system is never idle, always utilized to its full capacity for best possible

productivity. • Intuitive operationThe GERSTEL MAESTRO software lets you operate your MPS by mouse-click whether it is operated

independently or integrated with the analysis system. MAESTRO operates fully integrated with the

Agilent ChemStation or GC MassHunter. One method and one sequence table control the complete

system from sample preparationto GC/MS or LC/MS analysis. MAESTRO operates integrated with the

sequence tables of Agilent LC MassHunter, AB Sciex Analyst®- and ThermoFisher Scientific XCalibur.

• Maximum fl exibilityThe MPS lets you automate a wide range of standard or special sample preparation technologies.

Whenever it is needed, the MPS easily and quickly adapts to the task at hand.

THE NEW

Versatile autosampler and sample preparation robot for

your analytical labModern laboratory processes frequently offer significant potential for improve-

ments in the fields of sample preparation and -introduction. Improving productivity

and performance while cutting per sample cost is realistic provided you have cho-

sen an autosampler that rises to the task and can be adapted to meet new challen-

ges as demands change. The GERSTEL MultiPurpose Sampler MPS enables highly

efficient automation of sample preparation and sample introduction for GC/MS

and LC/MS. Or you can use the MPS as WorkStation independent of the analysis

systems, providing prepared samples for multiple techniques in the lab. Whichever

MPS you choose, you are sure to get reliable results and increased throughput

combined with the flexibility to adapt effortlessly to changes and new challenges.

The MPS is not just an attractive addition to your lab:

1. Routine tasks are performed reliably - every day.

2. Your analytical instrument is utilized to full capacity,

sample preparation and analysis are performed in

parallel and synchronized for optimum throughput.

3. Set up your daily analysis sequence or add priority

samples with a few mouse-clicks using the intelligent

MAESTRO software.4. MAESTRO works fully integrated with the Agilent

ChemStation and GC/MS MassHunter and integrated with

the Agilent LC/MS MassHunter, AB Sciex Analyst® and

ThermoScienti� c XCalibur sequence tables.

Your benefi t:5. Your entire analysis from sample preparation to GC/

MS or LC/MS analysis is controlled from one software

platform, fully integrated or, in some cases, using one

integrated sequence table.

✔

✔

✔

✔

✔

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text

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Versatile autosampler and sample preparation robot

This is what the new MPS offers you:

Effi cient, produktive, reliableThe GERSTEL MultiPurpose Sampler MPS performs your routine analysis tasks efficiently

and reliably. You benefit from the rugged and proven technology. To operate the system,

method and sequence generation requires very limited training and no programming

knowledge whatsoever. In almost no time, using only a few mouse-clicks, you have

set up the system for preparation and analysis of your daily sample load – or for the

weekend batch. And if you need to add priority samples when the system is running –

no problem! Without stopping the ongoing analysis, you simply insert the priority sample

into the sequence table and specify its position: As soon as the system has finished the

ongoing analysis, the priority sample will jump the queue and be processed.

Flexible through and throughYou can handle almost any application challenge with the MPS. The modular concept

enables you to react flexibly to new analytical demands. New sample preparation me-

thods are quickly and easily generated using the MAESTRO PrepBuilder, available sample

preparation options are easily activated or deactivated in the method and set-up, enabling

you to react fast to newly arrived samples and to demands for new analysis methods.

The MPS can be integrated into your analysis system combining sample preparation with

sample introduction to your GC/MS or LC/MS – or it can be operated independently as a

WorkStation, preparing samples for multiple analytical systems in the lab. R&D: In the field of research and de-

velopment, analysts benefit from the

modular concept of the MPS, which

enables fast and simple adaptation to

constantly changing requirements and

to new challenges. A wide range of

sample preparation modules and tech-

nologies are available from GERSTEL.

You can easily and conveniently elimi-

nate matrix residue from your sample or

extract, add internal standards or deriva-

tization reagent to improve the quality

and limits of determination of your analysis – or change the solvent as

needed to enable GC or HPLC analysis.

Different sample preparation steps are

combined easily and conveniently by

mouse-click.

Routine analysis: Laboratory work is

not routine until you can perform it wit-

hout paying too much attention. Uncom-

plicated and reliable operation combined

with results you can trust and safely report

to your clients – those are attributes of

laboratory set-ups that are based on the

GERSTEL MPS. The MPS has a proven

record of providing first class sample

preparation and sample introduction for

GC/MS and LC/MS. The MPS can be com-

bined with any standard chromatography

system, the intelligent MAESTRO software

control will help ensure that the combined

system is utilized to its fullest capacity

providing best possible productivity and

throughput. You set up the sequence table

for the day or for the weekend; the MPS

takes care of the rest.

Benefi ts for R&D and routine analysis

2 GERSTEL Solutions Worldwide – No. 11

Dear reader, It is the goal of GERSTEL Solutions Worldwide magazine to take you on an excursion through the world of chemical analysis to laboratories all over the globe that use GERSTEL solutions in their daily work. Technical aspects regarding the instrumentation used are of course important, but first and foremost we want to focus on the application. In the 11th issue of our magazine, we report on several interesting themes ranging from the highest mountains to the deep blue sea: We visit the Andes with a team of scientists to find traces of polychlorinated biphenyls (PCBs) on the Cerro Aconcagua, the highest mountain in the Americas. We report on how pesticides can easily and efficiently be determined in food and we look at how the largest oil spill in recent history has brought a lot of changes to chemical analysis applications in the field of food safety. Further, we go on a sensory tour de force, poking our nose and our Twisters in wine, whiskey and other beverages looking for desirable and undesirable flavors. Last, but not least, the centerfold in this issue is an attractive and informative addition, featuring the new GERSTEL MPS, which forms the basis for much of the application work we present.

The GERSTEL MPS has been installed in several thousand laboratories over the years making it one of the most widely sold sample preparation and sample introduction robots for GC/MS and LC/MS. Externally, the sleek and modern look is the first thing that strikes most people when they see the new MPS. As always, the magic is in the detail…

Enjoy the magazine! Sincerely,

E b e r h a r d G . G e r s t e l President / Co-Owner

Eberhard G. Gerstel

Externally, the sleek and modern look is the first thing that strikes most people when they see the new MPS. As always, though, the magic is in the detail. The electronics of the MPS have been unified and brought up to the latest standards. A LAN port was added along with additional memory capacity giv-ing the analyst more freedom to operate with multiple instru-ment configurations. The new MPS sup-ports all GERSTEL sample preparation and sample intro-duction technologies. All options are easily and intuitively oper-ated using the MAE-STRO software. The PrepAhead func-tion enables paral-lel sample prepara-tion and analysis, perfectly synchro-nized for optimized system utilization. The GC/MS or LC/MS system typically never has to wait for the next injection when it becomes ready after a run. MAESTRO oper-ates independently or fully integrated with Agilent ChemStation or GC MassHunter. The new MPS helps you further improve per-formance and productivity of your GC/MS or LC/MS analysis.

Innovation

The new MPS: Driving productivity

Since its introduction, the GERSTEL MPS (MultiPurpose Sampler) has been installed in several thousand laboratories, making it one of the most widely sold sample preparation and sample introduction robots for GC/MS and LC/MS. With this kind of success, it only makes sense to stick with the proven concept when developing the next generation. The new MPS delivers improved productivity and performance and provides an advanced platform

for future developments.

A glance at the application details pro-vides some clues to the added value that the MPS can bring to your lab. The MPS helps you automate your sample preparation:

Matrix residue is eliminated using SPE or dispersive SPE (DPX); standards or reagents can be added; dilution series created; ana-

lytes concentrated for improved lim-i t s o f detec t ion , for example, using D y namic Head-space (DHS), Stir Bar Sorptive Extrac-tion (SBSE) or Solid Phase Micro-Extrac-tion (SPME).

An innovation in the range of options is Dynamic Load & Wash (DLW), which is used to eliminate carry-over between LC/MS injections.

A l l s a m p l e preparation steps are easily, flexibly and intuitively entered by mouse-click in the MAESTRO software, and the daily sequence table is quickly generated using intelligent fill-down and copy functions.

The new MPS is your reliable platform for GC/MS and LC/MS sample preparation and sample introduction for the coming years.

More details ...

about the new MPS can be found in the centerfold insert in this magazine.

GERSTEL Solutions Worldwide – No. 11 3

Snow is a fascinating material - and not just in the eyes of children of all ages rac-

ing down snowy slopes on a sunny winters day. Even scientists preoccupied with the whereabouts of persistent organic pollut-ants (POPs) in the environment can appar-ently develop a weakness for snow. Chilean, Spanish, and German scientists, among them experts from the Helmholtz Center for Envi-ronmental Research (UFZ) in Leipzig, Ger-many, went on an expedition to South America. Their goal was the eternal snow cap of the Cerro Aconcagua, at 6962 meters the highest moun-tain in the Americas. In the elevated snow repos-itory, the scientists hoped to find deeper answers to the whereabouts and long range atmospheric transport of polychlorinated biphenyls (PCBs) in the southern hemisphere.

Environmental

POP traces in icy heights

A team of scientists from Chile, Spain and Germany have found polychlorinated biphenyls (PCBs) in the snow of the high Andes Mountains at elevations above 6000 meters. While the GC/MS analysis involved is straight forward, new paths had to be trodden to improve the sample preparation and reduce the amount of sample that needed to be carried to the laboratory. The scientists found an ultra-sensitive solution: Stir Bar Sorptive Extraction (SBSE).

PCBs along with several pesticides, industrial chemicals and incineration products belong to the «dirty dozen» of organic chemicals that are also known as persistent organic pollutants (POPs). The Stockholm Convention on Per-sistent Organic Pollutants is an international environmental treaty that aims to eliminate or restrict the production and use of POPs. The treaty was signed in May 2001, outlaw-ing nine of the «dirty dozen» chemicals, lim-iting the use of DDT to malaria control, and curtailing inadvertent production of diox-ins and furans. Until the 1980‘s, PCBs were widely used as insulating oil and refrigerant in transformers and capacitors, as hydraulic flu-ids, and as plasticizers. According to the US EPA, PCBs have been demonstrated to cause adverse health effects in animals such as can-

An expedition of scientists crosses the Poland glacier during the ascent of the east-ern slopes of Cerro Aconcagua (6962 m), the highest mountain in the Americas. The mission of the scientists is to sample snow at levels above 6000 meters to determine the accumulation of airborne pollutants brought to the southern hemisphere by long range atmospheric transport (LRAT).


cer and a number of serious non-cancer health effects, including effects on the immune sys-tem, reproductive system, nervous system, endocrine system and other health effects. Studies in humans provide supportive evi-dence for potential carcinogenic and non-car-cinogenic effects.

PCBs accumulate in fat tissue and reach the human body through the food chain. To determine the degree to which PCBs are present in the environment, samples must be taken and chemical analysis performed. This is the only way to gauge whether interna-tional treaties are being adhered to. But why head for the glaciers in the high Andes with your back pack? Scientists agree: Due to their high porosity and resulting high specific sur-face, ice crystals are more efficient than rain drops at extracting pollutants from the atmo-sphere. The only condition that must be met is that temperatures permanently stay below the freezing point of water to conserve the fallen snow until it is sampled, and temper-atures below 0 °C is a given at 6000 meters above sea level. The idea behind the project of the scientists was to analyze the icy precip-itate in order to gain insights as to the type, accumulation, and transport paths of POPs in the atmosphere.

POPs like PCBs and organochlorine pesticides are mainly deposited and accumu-lated in colder regions of the world accord-ing to an article by Quiroz et al. in Envi-ronmental Chemistry Letters (2009, 7: 283-288). Studies of PCB concentrations in snow from the arctic region and from the highest elevations in Europe and Canada have fur-ther shown that pollutants are distributed globally through Long Range Atmospheric Transport (LRAT). In the Andes Mountains, PCBs have been found in snow as well as in various solid, liquid, and gaseous matrices.

Influence of High Mountain Ranges

In the snow of the high Andes, Roberto Quiroz and his colleagues discovered mainly the most stabile PCBs such as hexachlorobi-phenyl (PCB 138) and heptachlorobiphenyl (PCB 180). Swiss scientists have previously found comparable pollution patterns in Swiss alpine glacier lakes and have pointed out the possible danger to drinking water supplies. Apparently, major mountain ranges like the Andes form a natural barrier for those POPs that are distributed globally through the atmosphere. The Spanish-, German-, Chil-ean team of scientists arrived at the conclusion that the effect of high mountain ranges on air-borne distribution of pollutants has been underestimated. The scientists recommend that this effect, and the processes involved, be investigated further. Since high mountain regions can be inaccessible, or at least diffi-cult to reach, environmental testing can be an enormous challenge or even a life-threaten-ing adventure. Adding to the misery, pollut-

PCBs are a group of highly stable chlorinated aromatic hydrocarbons containing from one to ten chlorine atoms. A total of 209 differ-ent PCB compounds exist; these are normally referred to as congeners. The chemical frame of PCB molecules is formed by two phenyl rings that can rotate freely. The general chemi-cal formula for PCBs is C12H(10-n)Cln, where n denotes the number of chlorine atoms (n=1-10). Internationally, the Ballschmiter nomenclature has prevailed, assigning a num-ber up to 209 to each congeners. The order is decided by the number of chlorine atoms in the molecule as well as by their individ-ual position. Such a numbering system is for example also used for polybrominated di-phe-nyl ethers (PBDEs). Even though they have been banned since the early 1980’s, due to

their resistance to photolytic, biological and chemical decomposition, PCBs and polychlo-rinated terphenyls are still ubiquitous. They accumulate in the food chain and can cause significant health- and environmental prob-lems. In case of fire or incomplete incinera-tion, polychlorinated biphenyls and polychlo-rinated terphenyls can form toxic chlorinated dibenzofuranes. PCBs belong to the group of „Persistent Organic Pollutants“ (POPs) that are classified as especially dangerous indus-trial chemicals by the United Nations Envi-ronment Programme (UNEP). PCB produc-tion, use and import were banned in Japan in 1972. The United States Congress banned PCB production in 1979, and in the Federal Republic of Germany, PCBs have not been produced since 1983.

Polychlorinated Biphenyls (PCBs)

ant concentrations are often very low. This, according to Quiroz et al., means that in order to reach the required lower limits of determi-nation large sample volumes have to be lugged over long distances under adverse conditions from alpine glaciers at very high altitudes to the laboratory. The international team of sci-entists therefore started out by investigating how the analysis could be performed satisfac-torily based on smaller, more easily transport-able sample amounts.

It‘s all about the extraction technique

The solution to the high-altitude conundrum was found to be Stir Bar Sorptive Extrac-tion (SBSE) using the GERSTEL Twister. The Twister is a patented magnetic stir bar covered with a thick layer of polydimethyl-siloxane (PDMS), a highly efficient sorbent

and extraction phase. While the Twister stirs the aqueous sample, organic chemical com-pounds are efficiently extracted and absorbed into the PDMS. Using thermal desorption, analytes are subsequently transferred quanti-tatively to a GC/MS system resulting in ultra-high sensitivity and lowest possible limits of determination. Depending on the analytes in question and the sample volume extracted, SBSE can be up to 1000 times more sen-sitive than SPME. SBSE is extremely sim-ple to perform. The Twister is added to the sample and allowed to stir for 1-2 hours. The Twister is then removed, dried using lint-free paper cloth, and placed in the autosampler tray. Thermal desorption is performed using a GERSTEL Thermal Desorption System (TDS) or Thermal Desorption Unit (TDU) in combination with a MultiPurpose Sam-pler (MPS). Either system can be connected with a GC/MS system that is used to sepa-rate and determine the individual compounds.


The UFZ was responsible for analyzing the snow samples: „While we needed at least one liter of snow to perform one analysis using conventional solvent-based extraction tech-niques, the solvent-free SBSE technique gave us the correct answer based on only a 40 mil-liliter sample“, Dr. Peter Popp said. This was an invaluable difference: „During expedi-tions at high altitudes, every gram counts. We could never have transported that many liters of snow. That is why we were delighted that just 40 milliliters of sample was suffi-cient“, Roberto Quiroz from IIQAB, Barce-lona added.

Sampling in dizzying heights, analysis in the laboratory

Quiroz took part in a 2003 rope party that took snow samples at 3500, 4300, 5000, 5800 and 6200 meters altitude on the eastern slopes of the Aconcagua. Samples were taken in 100 mL brown glass bottles and stored at -20 °C until analyzed. In the laboratory, samples were melted at room temperature. A 40 mL sam-ple of snow melt water was transferred to a 100 mL Erlenmeyer flask along with 10 mL of MeOH. The mixture was stirred for four

TDSA/TDS-GC/MS system used at the UFZ for automated desorption and analysis of up to 20 Twisters. As an alternative, the Thermal Desorption Unit (TDU) in combination with the MultiPurpose Sampler (MPS) performs automated analysis of up to 196 Twisters in one batch.

The GERSTEL Twister is small and easy to handle: For sensitive determination of PCBs in water, only a 40 mL sample is needed. An important fact, especially when samples have to be carried in your personal back pack at 6000 meter elevation, where every gram counts. For thermal desorption and GC/MS determination of the analytes, the Twister is placed in a sealed glass liner.

Literature

Quiroz, R., Popp, P., Barra, R.: „Analysis of PCB levels in snow from the Aconcagua Mountain (Southern Andes) using the stir bar sorptive extraction.“ Environmental Chemistry Letters 7 (2009), 283-288

Chromatogram resulting from a snow sample taken at 6200 Meter elevation: Finding PCBs on the highest point of the Andes is proof of long-range atmospheric transport (LRAT) and accumulation of persistent organic pollutants (POPs) in the Southern hemisphere.

hours using a Twister, whereby the PCBs in the sample were concentrated in the PDMS phase of the Twister. The Twister was then removed from the flask, dried, and placed in an empty thermal desorption glass tube.

Ultra-low limits of determination and surprising results

Thermal desorption of the Twister was per-formed using a Thermal Desorption System (TDS) equipped with a TDS A autosampler. If larger numbers of samples need to be ana-lyzed, the GERSTEL Thermal Desorption Unit (TDU) in combination with the Mul-tiPurpose Sampler (MPS) analyzes up to 196 Twisters in one batch. Twisters were thermally desorbed at 250 °C for 10 minutes. Helium carrier gas flow at 100 mL/min was used to transfer analytes to the Cooled Injection Sys-tem (CIS), where they were cryofocused at -20 °C. The CIS was then heated to 250 °C at a rate of 12 °C/s. Analytes were transferred to the GC column in splitless mode, the split was reopened at 2.0 min. The separation was performed on an Agilent HP-5MS column (30 m, 0.25 mm ID, 0.25 µm film thickness) using the following temperature program:

Starting temperature: 70 °C; 2 min hold; 15 °C/min to 180 °C; 10 min hold; 5 °C/min to 280 °C; 10 min hold. A GC/MS sys-tem from Agilent Technologies was used (GC 6980/MSD 5973). Analytes were detected in SIM mode using two characteristic ions.

Dr. Popp and the UFZ team analyzed the snow samples to determine a total of 25 PCBs. The SBSE-TDS-GC/MS method enabled recoveries between 85 and 93 per-cent on average. The limit of detection was 0.02 ng/L. In the Aconcaqua snow samples, the scientists mainly found the most persis-tent congeners PCB 138 and PCB 180, albeit in concentrations below 0.5 ng/L. This is a relatively low concentration compared with samples from other mountainous and cold regions in the world, leading Quiroz and his fellow scientists to conclude that the South-

ern Hemisphere is less polluted than the Northern Hemisphere. The presence of PCBs does prove, however, that these compounds are transported to and deposited in the Andes. The results of this research could gain addi-tional relevance given the background of global climate change. „If the glaciers were to melt or partially melt, the deposited chemical pollutants would be washed down-stream and could contaminate the local drinking water“, says Roberto Quiroz. And it is not only in South America that glaciers play an impor-tant role as a source of drinking water and water for irrigation.


This much seems certain, nobody can really tell how the marine biosphere will respond

to the trauma - or to the treatment for that matter. Following the unprecedented oil spill in the Gulf of Mexico that lasted almost three months, the environment has had to contend with the two-pronged attack of crude oil and of chemicals added to the cocktail to disperse the black gold. But which traces will remain? - And will toxic com-pounds accumulate? - And where? These are among the questions being posed. And, as always, the main focus of attention is poten-tial direct health effects to humans. The main interaction between man and the environment of the Gulf of Mexico is through the plentiful supply of seafood harvested there. There has been general agreement that pollutants could wind up in our food and, notably, that polyaro-matic hydrocarbons (PAHs) could accumu-late through the food chain and be served up in concentrated form on a seafood plat-ter. If so, what could appropriate measures to counter the threat look like? The answer and first step has been to implement com-prehensive controls. As it turns out, every answer gives rise to new questions: The offi-

cial method used to determine PAH levels in seafood is NOAA NMFS-NWFSC-59, which relies on Accelerated Solvent Extrac-tion (ASE), two separate evaporative concen-tration steps, liquid chromatography clean-up, and finally GC/MS analysis. Following this method means that typically only one batch of 14 samples and associated standards

can be analyzed per week in most laborato-ries. When faced with a mountain of samples, initial estimates ran as high as 10,000 sam-ples per month, more efficient methods will have to be found.

Extraction technique of choice The authors of a recent publication set out to find a more efficient and practicable quanti-

The oil well disaster in the Gulf of Mexico could have wide-ranging consequences for the environment and potentially for the tens of thousands who make a living from delivering seafood to our plates. Closer to home, consumers are still pondering whether it is safe to put seafood on the menu. A simple answer is not easy to come by, but government and industry resources at many levels have been actively focusing on the issue. Analytical labs have been working overtime using cumbersome regulated methods while trying to find new and more productive ways to analyze the mountain of samples before them. As always, when we rise to a challenge, new and sometimes unexpected

answers are found.

Polyaromatic seafood platter?

tative analysis method for PAHs in seafood, performing a study to determine if using a QuEChERS (Quick, Easy, Cheap, Effected, Rugged, and Safe) extraction method in con-junction with Stir Bar Sorptive Extraction (SBSE) could meet regulatory limits of detec-tion and requirements established for preci-sion and accuracy. SBSE has proven its worth

for many challenging matrices over the past decade. A recent EPA Region 7 study has shown that SBSE is an effective and fast technique for trace PAH deter-mination in water. The results of the study were presented in May 2010 at the 58th American Society for Mass Spectrometry (ASMS) Conference.

SBSE relies on the GERSTEL Twister™, a glass coated magnetic stir bar with an exter-nal layer of polydimethylsiloxane (PDMS). While stirring the sample, the Twister effi-ciently extracts organic compounds into the PDMS phase. Following the extraction step, the Twister is removed from the sam-ple, quickly dried with a lint-free cloth and placed in a thermal desorption tube. The tube and twister are then placed in an autosampler tray, in which the tube is kept sealed to elim-

Food Safety

„Increasing sample throughput to 40 samples per day as opposed to 25 samples per week, is invaluable and will greatly assist response efforts aimed at determining sea-food safety.“

Jeffery H. Moran, Public Health Laboratory, Arkansas, USA


Calibration curve for Benzo[a]pyrene determined in spiked oys-ters. d12-perylene was added as internal standard (IS) to the sample resulting in a concentration of 25 ppb IS in the sample. Further, the following deuterated internal standards were used: for the analytes naphthalene and fluorene: d8-naphthalene; for anthracene and phenanthrene: d10-phenanthrene; and for fluoranthene, pyrene, benz[a]anthracene and chrysene: d12-chrysene.

inate the risk of contamination. Ther-mal desorption of one or more Twist-ers is performed, for example, in the GERSTEL Thermal Desorption Sys-tem (TDS) or Thermal Desorption Unit (TDU) and the analytes are trans-ferred directly and quantitatively to the GC/MS system.

Principle

Compared with the NOAA method mentioned earlier, the QuEChERS-SBSE-GC/MS method is a revolu-tion, no less; the QuEChERS method uses a single-step acetonitrile (ACN) extraction and liquid–liquid partition-ing based on salting out from the water in the sample using MgSO4. The orig-inal QuEChERS procedure for pesti-cides includes dispersive-solid-phase extraction (dSPE) cleanup to remove organic acids, excess water, and other components with a combination of pri-mary secondary amine (PSA) sorbent and MgSO4. However, this cleanup step provides no additional concentra-tion factor making it difficult to achieve detection limits meeting the current requirements for PAH analysis. The procedure used in the work reported here includes using SBSE as a com-bined cleanup and concentration step, eliminating organic acids and other polar and high molecular weight matrix components and providing a substantial concentration factor to easily achieve the regulatory detection limits. In brief, 3 g of a homogenized seafood tissue sample in water is extracted with ACN in a 50 mL centrifuge tube followed by addition of 6.0 g MgSO4 and 1.5 g sodium acetate which is shaken and centrifuged. A portion of the ACN extract (upper layer) is added to a 10 mL vial along with 4 mL 0.1 M NaHCO3 and a GERSTEL Twister™ stir bar that is used to extract and concentrate the PAHs. The Twister is removed from the sample extract, rinsed with DI water to remove matrix residue, dried with a

Extract of an oyster sample (3 g), spiked with a mixture (2,5 ppb) of naphthalene (1), fluorene (2), phenanthrene (3), anthracene (4), fluoranthene (5), pyrene (6), benzo[a]anthra-cene (7), chrysene (8) and benzo[a]pyrene (9).

Extract of a fish sample (3 g), spiked with a mixture (2,5 ppb) of naphthalene (1), fluorene (2), phenanthrene (3), anthracene (4), fluoranthene (5), pyrene (6), benzo[a]anthracene (7), chry-sene (8) and benzo[a]pyrene (9).

Extract of a shrimp sample (3 g), spiked with a mixture (2,5 ppb) of naphthalene (1), fluorene (2), phenanthrene (3), anthracene (4), fluoranthene (5), pyrene (6), benzo[a]anthracene (7), chry-sene (8) and benzo[a]pyrene (9).

Authors / More information

Jackie Whitecavage, Jack R. Stuff and Edward A. Pfannkoch GERSTEL Inc., Linthicum, MD 21090, USA.

Jeffery H. Moran Arkansas Public Health Laboratory, Little Rock, AR 72205, USA

For more information, please visit our website (http://www.gerstel.com/en/ applications.htm) to download the GERSTEL AppNotes 2010/6a and 2010/6b: High Throughput Method for the Determination of PAHs in Seafood by QuEChERS-SBSE-GC-MS.

lint-free cloth, placed in a TDU tube, and the TDU tube is placed in the Mul-tiPurpose Sampler (MPS) tray. From that point on, everything is automated. The Twister is thermally desorbed and analytes are transferred to the Cooled Injection System (CIS) GC inlet where they are cryofocused. Using a fast tem-perature program, the focused analytes are transferred in a narrow band from the CIS inlet to the GC column, pro-viding the best possible basis for a clean GC separation and ultra-low limits of detection. The system used combined a GERSTEL MPS, TDU and CIS 4 with a GC/MS System from Agilent Technologies (GC 7890/MSD 5975). Using this method, at least 40 samples can be analyzed per day.

Conclusion The scientists showed that QuECh-ERS and SBSE extraction is an excel-lent alternative to the currently used NOAA NMFS-NWFSC-59 method used for the determination of PAHs in seafood matrices. SBSE was able to out-perform the NOAA method on multi-ple counts:

1) Efficient, easy, and conveniently automated, SBSE-GC/MS dramat-ically improves sample throughput, which is especially important when a large number of samples need to be ana-lyzed or screened.

2) Even though the NOAA method relies on two evaporative analyte con-centration steps and LC clean-up, QuEChERS-SBSE-GC/MS provides limits of detection that are a factor 10 – 50 lower. Reducing the 1:10 split ratio used in the SBSE-GC/MS method would further improve detection limits.

3) The QuEChERS-SBSE-based method significantly reduces the amount of solvent needed. This saves cost, protects the environment, and reduces the amount of solvent in the laboratory air thereby improving occu-pational safety for laboratory staff.

Concentration [ppb]

Peak

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IS


Y ou don’t have to be a sommelier or wine expert to tell the difference between a per-

fect wine and a corky wine. 2,4,6-trichloroani-sol (TCA) has an extremely low odor thresh-old. As little as a few nanograms per liter of air is enough to detect an unpleasant musty off-flavor. In water and wine it is a similar story with odor thresholds at 0.3 ng/L and 1.4 ng/L respectively, “but that is only a theoret-ical value”, says Horst Rudy from the Agri-cultural Service Center (DLR) of the Mosel wine region in Germany. “After all”, the lab-oratory manager explains, “sensory perception is highly individual and very subjective: While one consumer may sense no problem even at

Off Flavors in Wine: Corky

When your premium wine tastes corky, it is little consolation that this is not caused by the natural cork material used to produce the classic wine stopper. Corkiness points to the presence of 2,4,6-trichloroanisol (TCA), the most well-known malodorous culprit. But other chemical suspects are at large that can equally cause the unpleasant musty, moldy off-odor assault to your nose, and these may not even be coming from the cork stopper. To ensure an efficient, reliable and sensitive determination of all corkiness-related off-flavor compounds, the DLR Mosel in

Germany successfully turned to GC/MS combined with Stir Bar Sorptive Extraction (SBSE).

Efficient and sensitive determination of

TCA and other off-flavors

much higher concen-trations, another per-son’s olfactory bulbs sets off the mal-odor alarm at concentration lev-els as low as 0.5 ng/L”. In addition, several fac-tors could influence sen-sory perception of the off-flavors; among these are sweetness, alco-

hol content and grape type. “Whoever wants to identify corky off-flavor com-pounds and track down their source has no choice but to use gas chromatogra-

Horst Rudy

phy combined with mass selective detection (GC/MS)”, Horst Rudy points out.

Barking up the wrong tree – on the origins of Corkiness

The usual suspect as a source of 2,4,6-TCA is the cork stopper made from the bark of the cork oak tree (Quercus suber). TCA is a microbial metab-


Calibration curve for 2,4,6-tri-chloroanisol (TCA): Limit of detection: 0.39 ng/L; Limit of determination: 0.79 ng/L

2,4,6-TCA Area TCA / concentration Area ISTD [ng/L] 1 0.38642 2 0.69888 3 0.98844 4 1.36316

Calibration curve for 2,4,6-tri-bromoanisol (TBA): Limit of detection: 0.50 ng/L; Limit of determination: 1.0 ng/L

2,4,6-TBA Area TBA / concentration Area ISTD [ng/L] 1.2 0.20709 2.4 0.45745 3.6 0.64190 4.8 0.85998

Limit of Detection Odor thresholds 2,4,6-Trichloroanisole (TCA) 0.3-0.5 ng/L 1.4 - 4 ng/L2,4,6-Tribromoanisole (TBA) 0.5 ng/L 3 - 8 ng/L 2,3,4,6-Tetrachloroanisole (TeCA) 1.1 ng/L 4 - 24 ng/L 2,4,6-Trichlorophenol (TCP) 1.4 ng/L 4000 ng/L 2,4,6-Tribromophenol (TBP) 1.6 ng/L Pentachlorophenol (PCA) 0.9 ng/L 4000 ng/L

Limits of detection and odor thresholds of the corkiness-causing compounds determined using SBSE-GC/MS.

File TCA [ng/L]Day 1 1511041 6.1 1511042 4.9 1511043 4.7 1511044 4.5Day 2 1511045 8.5 1511046 6.4 1511047 5.4Day 3 1511048 7.4 1511049 6.1 15110410 5.3

Standard deviations under real laboratory conditions. A 1.5 L sample of water used to wash cork material was homogenized and ten separate aliquots were extracted using SBSE (GERSTEL Twister). GC/MS analyses were performed over three consecutive days. Mean value: 5.9 ng/L; standard deviation s = 1.26 ng/L; Minimum value 4.5, maximum value 8.5 ng/L.

olite, formed by methylation of trichlorophe-nol (TCP) that may have been applied to the bark as a pesticide. To suspect the cork stop-per of introducing TCA to the wine is there-fore only logical according to the wine expert, but when wine drinkers started experiencing corkiness in wines with modern polymer-based stoppers experts knew that they had been barking up the wrong tree.

Over the course of the ensuing research projects, it was found that various com-pounds, mainly halogenated anisols, would give a musty, moldy note to the wine. These compounds could be formed from other chlo-rinated chemicals that are used for cleaning of wine production equipment or for treat-ing wooden transport pallets or packaging material

Until the end of the 1980’s, pentachloro-phenol (PCP) was used as a fungicide to pro-tect, for example wooden pallets from micro-bial decay. Among others byproducts, PCP contained 2,3,4,6-tetrachlorophenol (TCP), a compounds that is metabolized microbially to 2,3,4,6-tetrachloroanisol (2,3,4,6-TeCA, TeCA), which also causes corkiness in wine.

Corkiness-related off flavor compounds found in wine: 2,4,6-trichloroanisole (TCA [1]) and 2,4,6-tri-bromoanisole (TBA [2]).

1

2

SIM chromatogramof 2.4 ng/L TBA

SIM chromatogramof 1.0 ng/L TCA

to 2,4,6-tribromoanisol (2,4,6-TBA), a com-pound given the sensory attributes musty, earthy, and chemical with a smell of solvent. “TBA is a corkiness causing compound of the first order”, Horst Rudy points out.

Chemical analysis and sensory evaluation – complementary techniques

When the DLR Mosel is asked to deter-mine the cause of a musty and moldy off flavor in a wine, sensory evaluation is only the first step in the process. “While corky off-flavors are typically determined quite reliably”, Horst Rudy says, “TCA concen-trations at or below the odor threshold of-ten lead to a subtle and indefinable change in the wine flavor, not perceived as a corky flavor note”. In such cases, chemical analysis is needed in order to prove that the wine is under the influence of TCA. To snoop out the source of the contamination, all aspects of the wine production and bottling pro-cess, as well as the entire production site environment, must be carefully investigated. Horst Rudy and his team deploy passive samplers based on Bentonite clay to pick up TCA traces. “Passive samplers are easy to work with and they deliver valuable in-formation such as a distribution profile enabling us to more accurately localize the source”, says Mr. Rudy. As a general rule, the DLR does not restrict its GC/MS in-vestigations to off-flavors that are perceived as corky. Among the targeted compounds are: 2,4,6-trichloroanisol (TCA), 2,4,6-tri-bromoanisol (TBA), 2,3,4,6-tetrachloro-anisol (TeCA), 2,3,4,5,6-pentachloroanisol (PCA), as well as the TCA and TBA pre-

In animal tests, PCP was found to be car-cinogenic. In Germany, the use of PCP has been prohibited since 1989. PCP was substi-tuted by 2,4,6-tribromophenol (TBP), a com-bined fungicide and flame retardant, which is often used to protect cardboard packaging, polymer materials, paints and coatings. As it turns out, microorganisms metabolize TBP


Step by step: How to extract odor active compounds

from wine or water using the GERSTEL Twister

Instead of six hours per analysis, the Twister based analysis only requires 1.5 hours in order to determine the concentration of corkiness-related off flavor compounds. Multiple samples can be processed simultaneously.

cursors 2,4,6-trichlorophenol (TCP) and 2,4,6-tribromophenol (TBP), which are less odor-active. The presence and distri-bution of TCP and TBP can give valuable information as to the source of an off-flavor. To determine the identity and concen-tration of odor agents, cork stoppers are extracted for two hours in a 10 % ethanol-water mixture using sonication to speed up the process. The bentonite clay used for passive sampling is extracted in the same way. Subsequently, 100 mL of the Ethanol solution is extracted for one hour by Stir Bar Sorptive Extraction (SBSE) using a GERSTEL® Twister™ (The bentonite should be allowed to precipitate before sampling is performed). The Twister is a glass-coated magnetic stir bar with an outer Polydimethylsiloxane (PDMS) layer. While the Twister stirs the sample, ana-lytes are extracted and concentrated into the PDMS phase. Depending on the ap-plication and on the sample volume avail-able, SBSE can be up to 1,000 times more sensitive than SPME due to both the sig-nificantly larger PDMS volume available and to the larger sample volumes extracted. Quantification in this work was performed using 2,4,6-trichloroanisol-D5 as internal standard.

Fast and sensitive analysis using the GERSTEL Twister

The multi-stage liquid-liquid extraction pre-viously used by DLR Mosel was highly labor- and cost intensive. “Sometimes I spent all day in the laboratory and still only managed to analyze four samples”, states Mr. Rudy. More modern analysis techniques, such as Solid

Phase Micro-Extraction (SPME) enabled the DLR to reduce the analysis time signifi-cantly, but the limits of detection achieved, for example 2.9 ng/L for TCA, meant that this technique was only of limited use. “We have to reliably determine concentrations of odor-active compounds at their odor threshold lev-els”, says Horst Rudy, “and for this reason we started using SBSE and the GERSTEL Twister”. SBSE is a fast and accurate extrac-tion technique that enables the DLR labora-tories to reach a detection limit of between 0.3 and 0.5 ng/L for TCA as per the DIN 32645 method and the analysis time has been reduced from 6 hours to 1.5 hours per sam-ple and multiple samples can be processed in parallel for improved productivity.

SBSE is extremely easy to perform: Following the extraction step, the Twister is removed from the sample, dried using a lint-free paper cloth and transferred to the autosampler tray. Up to 196 Twisters can be desorbed and analyzed by GC/MS in a single batch using the GERSTEL MPS and TDU directly mounted on a GC/MS system. The work reported in this article was performed using a GC 6890/MSD 5975 (Agilent Tech-nologies).

Place the Twister in the sample (1). While stirring the sample, the Twister concentrates analytes in its PDMS phase (2). The Twister is removed from the sample (3), dried with a lint-free cloth (4) and placed in the MPS tray (5) for automated thermal desorption in the TDU (6).

1

2

3

4

5

6Contact

Horst Rudy DLR Mosel, Dept. of Viticulture and Oenol-ogy, Egbertstrasse 18-19, 54295 Trier, Ger-many, Phone +49 (0)651/9776-187 or -185, -186 Fax +49(0)651/9776-193, E-mail: [email protected]


Tan Surakanpinit

Supporting a growing market for automated GC/MS and LC/MS solutions: GERSTEL LLP, Singapore

In order to support a growing customer base in South East Asia, GERSTEL has founded a wholly-owned subsidiary in Sin-gapore: GERSTEL Limited Liability Part-nership (LLP).

GERSTEL already has subsidiar-ies in the U.S.A., Japan, Switzerland, and Brazil. GERSTEL is also repre-sented in 70 other countries world-wide, by carefully selected and fully trained dis-tributors.

GERSTEL LLP will be run by Tan Surakanpinit. Ms. Surakanpinit was born in

GERSTEL on expansion course in South East Asia

Contact

GERSTEL LLP, Level 25, North Tower One Raffles Quay, Singapore 048583 Phone: +65 6622 5486 Fax: +65 6622 5999 E-mail: [email protected]

Thailand, where she studied Chemistry and later received her MBA. Ms. Surakanpinit brings extensive international experience in the chromatography laboratory instrumenta-tion business into her new position. Prior to joining GERSTEL, she held a range of posi-tions from Regional Sales & Business Devel-opment Manager to World-Wide Marketing Manager taking her to workplaces in Thai-land, The Netherlands, the U.S.A. and Sin-gapore.

Ms. Surakanpinit’s responsibilities will include supporting our distributors and developing new business opportunities in the Asia Pacific Territories, including Singapore, Malaysia, The Philippines, Taiwan, Vietnam, Thailand, Australia, and New Zealand.

Automated Multi-Desorption Mode is avail-able for the GERSTEL Thermal Desorp-tion System (TDS) and GERSTEL Thermal Desorption Unit (TDU). Analytes from a number of sample extractions can be desorbed and concentrated into a single GC/MS run, significantly increasing sensi-tivity and reducing limits of detection. Multi-desorption mode is activated by simple

selection in the MAESTRO configuration editor. In the sequence table, desorption of multiple adsorbent tubes or Twisters for every GC/MS run can then be spec-ified. Individual tube numbers or ranges can be chosen freely. For SBSE analy-sis, peak areas have been shown to be proportional to the number of Twisters desorbed.

Multi-Desorption Mode TD

New Subsidiary


GERSTEL on expansion course in South East Asia

Flavor and Fragrance Analysis

Put on the 1D/2D goggles...

The more complex the sample and the wider the concentration range of analytes, the bigger the challenge for the chromatographer to get a clean separation and sharp peaks. One short-cut is to heart-cut the challenging part(s) of the chromatogram to a 2nd dimension to get a full set of separated peaks. The patented new Selectable 1D/2D-GC/MS system enables simple and flexible switching between one- and two-dimensional GC/MS analysis on a

single GC/MS system.

Determination of flavors and allergens in food, cosmetics and personal care prod-

ucts is certainly not a trivial matter. The matrix is often complex, sometimes requiring extensive sample clean-up and up to several sample preparation steps. Efficient automated sample preparation is a good first step on the way to getting reliable results, but even well prepared samples can produce forests of over-lapping peaks making it a case of not being able to see the trees for the forest. When compound peaks overlap, or if a flavor emerges from the Olfactory Detection Port (ODP) without a detectable asso-ciated signal from the MS, multi-dimen-sional GC can be the solution that cuts through the thicket and provides clear, reliable answers where one dimensional GC can not.

Until now, performing multidimen-sional GC analysis has required the use of a dedicated system with two GCs cou-pled to each other. Due to the extra cost, and to the often limited utilization in the laboratory, such solutions don’t always provide the best return on investment (ROI). GERSTEL now offers a solution that can be used for routine analysis as well as for special challenges. The pat-ented GERSTEL Selectable 1D/2D-GC/MS system is a flexible solution, based on a single standard GC/MS sys-

can be described as follows: When questions arise regarding a section of the standard one-dimensional chromatogram, the section in question can be transferred to a 2nd dimen-sion, i.e. a GC column with different polar-ity installed in a separate module in the same GC. The process of cutting a section of a chro-matogram and introducing it to another col-umn is called heart-cutting. The GC system can be used to determine analytes in either

the 1st or the 2nd dimension in a flex-ible manner. Neither the GC run, nor analyte detection is interrupted during the run. Detection of the analytes that were transferred to the 2nd column is performed using the same detector(s) used for the 1st dimension: MSD, ODP, PFPD etc. etc. Should lower detection limits be required for the analyte in ques-tion, the system enables heart-cutting from multiple repeat injections com-bined with cryofocusing on a GER-STEL Cryo Trap System (CTS) of the sections that were cut. The cumulated sections are then transferred to the 2nd dimension column as soon as there is sufficient mass on column to reliably perform the determination. In order to speed up the analysis and eliminate interferences in the 2D chromatogram, the 1D column can be backflushed fol-lowing the heart-cut(s) in case no fur-

tem. It is, in short, a routine analysis sys-tem that offers heart-cutting, two-dimen-sional GC separation, and analyte concen-tration from multiple injections on demand. The MS detector is used in both dimensions to ensure clear and unequivocal peak identi-fication. Additional detectors, such as a PFPD sulphur-selective detector can be added to the system without modifying the hardware. In simplified terms, the method of operation

Figure 1. Schematic of the selectable 1D/2D-GC-MS system. Inter-esting sections of the standard 1D chromatogram can be heart-cut for separation on the 2D column. Analytes can be cryofocused using a GERSTEL CryoTrap System (CTS) positioned between the 1D and 2D columns. Heart-cut fractions from multiple injections can be cryofocused and combined into one 2D-separation for enhanced sensitivity. The 1D and 2D chromatograms and olfac-tograms are acquired on the same MSD and ODP.


Figure 2. Stacked view TICs of the 1st dimension chromato-gram (A) and the combined 1st and 2nd dimension chromato-gram (B) that results from heart-cut from 10–11 mins. Sample: 0.1 µg/mL bucchu ketone in water.

Figure 3. Stacked view peach flavor sample TICs of the 1st dimension chromatogram (A) and the combined 1st and 2nd dimension chromatogram that results from a heart-cut from 10–11 mins. (B). The absence of peaks in the 1D chromato-gram during the heart-cut period is evidence that eluting com-pounds are transferred efficiently to the 2D column.

Figure 4. Stacked view peach fla-vor sample TICs resulting from the desorption of 1 (A) and 5 (B)Twisters respectively. Heart-cuts were performed between the 1st and 2nd column from 10–11 mins. The combined 1st and 2nd dimension (1D/2D) chromato-grams are shown. In the bottom trace, the initial 1D part is from the 5th Twister desorption whereas the 2D chromatogram part results from accumulated heart-cuts from all five 1D runs. Analytes were focused on the GERSTEL CryoTrap System (CTS) between the 1D and 2D columns.

Analytical conditions

TDS Splitless 30 °C – 60 °C/min – 250 °C (5 min)

KAS Liner packed with glass wool Solvent venting (50 mL/min)

Peach flavor: Split (10:1) Gin: Splitless -150 °C – 12 °C/s – 280 °C (3 min)

Pneumatics Constant pressure

GC oven 250 °C isothermal

Column 1 (1D) 10 m Rtx-5 (Restek), LTM configuration, 0.18 mm ID. 0.18 µm film thickness (df)

Peach flavor: 40 °C (1 min) – 10 °C/min – 260 °C (0.8 min) – 100 °C/min – 40 °C

Gin: 40 °C (1 min) – 10 °C/min – 160 °C (0.8 min) – 140 °C/min – 300 °C

CTS Peach flavor: -50 °C (11.2 min) – 20 °C/s – 240 °C (2 min)

Gin: -50 °C (17 min) – 20 °C/s – 240 °C (2 min)

Column 2 (2D) 10 m DB-Wax (Agilent), LTM configuration, 0.18 mm ID, 0.18 µm film thickness (df)

Peach flavor: 40 °C (11.2 min) – 20 °C/min – 230 °C (1.5 min) – 50 °C/min – 40 °C

Gin: 40 °C (17 min) – 10 °C/min – 210 °C – 170 °C/min – 40 °C

MSD mode Full scan, 40-350 amu

ther compounds are deemed of interest. A schematic of the system is shown in figure 1. The GC columns used in the system are placed outside the GC oven in Low Ther-mal Mass (LTM) modules. The LTM tech-nology enables fast heating and cooling for faster analysis as well as independent temper-ature programming for each column mod-ule. The standard GC oven is merely used as a heated chamber for pneumatic connec-tors and switching devices. Keeping the GC oven at a fixed temperature contributes to the excellent system stability seen in our work with the system so far: Connectors are not subjected to cycles of heating and cooling with the associated material expansion and contraction that can eventually result in sys-tem leaks.

The analysis system and the sample preparation used

To check the performance under everyday routine analysis conditions, the selectable 1D/2D-GC/MS-system was used to de-termine bucchu ketone, which is the main flavor compound in peach flavor and is also found in gin. Typical samples have complex matrices resulting in countless interfering peaks. Because of this, multidi-mensional separation is the best means of getting information from peaks that oth-erwise would be hidden when using only 1D separation. With the addition of the ODP, the technique also provides valuable olfactory information from compounds that many times are not detected by the MSD.

The main components of the select-able 1D/2D-GC/MS system are as fol-lows: A GC 6890 equipped with a GER-STEL Cooled Injection System (CIS 4 - PTV-type universal inlet); two Low Thermal Mass (LTM) column modules; 5975C InertXL MSD (both from Agi-

lent Technologies); GERSTEL Thermal Desorption System (TDS) with TDS-A autosampler; as well as a GERSTEL CryoTrap System (CTS 2). Alternatively, a GERSTEL Thermal Desorption Unit (TDU) in combination with a Multi-Purpose Sampler (MPS) can be used instead of the TDS/TDS-A system. Stir Bar Sorptive Extraction (SBSE) was used to extract flavor compounds from both peach flavor and gin. SBSE is performed using the GERSTEL Twister, a glass encased mag-netic stir bar coated with PDMS.

While the Twister stirs the sample, ana-lytes are efficiently absorbed in the PDMS phase. Different Twisters are available with

different phase volumes. Depending on the phase volume the analyte, and the sample volume SBSE can provide up to 1000 times better sensitivity than SPME.

Successful implementation

Samples were prepared for SBSE as follows: Peach flavor sample: The sample was spiked to a concentration of 1 µg/mL bucchu ketone. 200 µL aliquots were pipetted into 10 mL screw cap headspace vials containing 9.8 mL bottled water to achieve a concentration of 0.02 µg/mL bucchu ketone in 10 mL of solu-tion. Gin sample: 0.5 mL aliquots of gin were pipetted into 10 ml screw cap headspace vials containing 4.5 ml bottled water.


Authors

Nobuo Ochiai and Kikuo Sasamoto, GERSTEL K.K., 2-13-18, Nakane, Meguro-ku, Tokyo 152-0031, JapanJohn R. Stuff and Jacqueline A. White- cavage, GERSTEL, Inc., 701 Digital Dr. Suite J, Linthicum, MD 21090, USA

Figure 5. 1st dimension TIC of gin sample.

Figure 7. Stacked view gin sample TICs resulting from the desorption of 1 (A) and 5 Twisters (B) respectively. Heart-cuts were performed between the 1st and 2nd column from 9.36-10.35 mins. The combined 1st and 2nd dimension (1D/2D) chromatograms are shown. In the bottom trace, the initial 1D part is from the 5th Twister desorption whereas the 2D chromatogram part results from accumulated heart-cuts from all five 1D runs.

Figure 6. TIC of gin sample: Combined 1st and 2nd dimension chro-matogram that results from a heart-cut from 9.36-10.35 mins.

A conditioned Twister was added to each vial. The vials were screw capped, and the samples stirred at room temperature for 1hr. Twisters were rinsed with water, dabbed dry, and placed into separate conditioned TDS tubes. The TDS tubes were finally placed in the TDS-A autosampler for analysis. All fur-ther steps were performed automatically. As a first step, the Twisters that had been used to extract the standard solutions were analyzed. Bucchu ketone was found in the retention time window between 10 and 11 minutes in the 1st dimension (1D) chromatogram. Per-forming a heart-cut of this time window resulted in a 2nd dimension (2D) chromato-gram with a number of peaks that could not have been separated in the 1st dimension (fig-ure 2).

The same approach was used for the peach flavor sample: A heart cut was per-formed of the retention time window from 10 to 11 minutes. The co-eluting compounds that were transferred to the 2nd dimension were separated on the 2D column and iden-tified. The 2nd dimension separation can fol-low either immediately after the heart-cut period or when the complete 1D separation has been finalized. The chromatograms from the two separations are acquired sequentially using the same MSD and combined into one GC/MS chromatogram. To ensure that late eluting analytes from the 1D column do not interfere with the 2D column chromatogram, the 1D column can be backflushed. In the case of the peach flavor sample, 1D column back-flush was not necessary, since no compounds from the 1D column co-eluted with the com-pounds separated on the 2D column (figure 3). In case the 2D column separation doesn‘t yield satisfactory answers due to lack of sen-sitivity it is possible to perform heart-cuts from multiple injections and to concentrate the transferred compounds by cryofocusing before releasing the combined fractions to the 2D column performing a single separation

and compound determination. To investigate the effectiveness of this approach, we cryofo-cused and then transferred five heart-cut frac-tions to the 2D column and compared the resulting chromatogram with one obtained from a single heart-cut fraction. The resulting chromatograms are shown in figure 4. Sharp peaks and excellent separation are obtained even after extended multi-step cryofocusing and the bucchu ketone signal is increased by a factor of 5.6 as can be seen in table 1. This result clearly shows the efficiency of the selectable 1D/2D-GC/MS system.

Table 1: Peak area for bucchu ketone as a function of number of twisters

The analysis of gin using the Selectable 1D/2D-GC/MS system provided highly satisfactory results, similar to the results for peach flavor mentioned above. To determine the bucchu ketone level in a gin sample, a heart-cut was taken from the 1D chromato-gram (Figure 5) between 9.36 and 10.35 min-utes and the fraction transferred to the 2D column. Transferring heart-cut fractions from 5 separate injections and cryofocusing these for a single 2D run resulted in a significant increase in sensitivity as can be seen in fig-ure 7.

Conclusion

Selectable 1D/2D-GC/MS has been used successfully in flavor and fragrance analysis, both for food, beverage, body care, and cos-metic products. In addition to flavors, off-flavors are an important application area for the 1D/2D technology. Off-flavors often need to be tracked down and determined both in the products themselves and in the packaging used and often the concentra-

tions involved are at ultra-trace levels. The 1D/2D system presented here provides the analyst with a powerful and comprehensive tool consisting of different polarity columns for multi-dimensional separation of a wide range of compounds even in complex matri-ces. Further the added capability to concen-trate flavor compounds from multiple injec-tions is extremely helpful when tracking down off-flavors with low odor thresholds. Since the complete solution is built into a single standard GC/MS system, investment costs remain very reasonable. Further, the heart-cut fraction can be analyzed on the 2nd dimen-sion column using the same MSD. Addi-tional detection possibilities such as a PFPD or an Olfactory Detection Port (ODP) can be integrated and used without adding com-plexity to the operation of the system. Unlike standard multi-dimensional GC/MS sys-tems, the 1D/2D system uses the MSD as monitoring detector for the 1D separation as well, ensuring that heart-cut sections are correctly chosen for the compounds in ques-tion and providing much additional infor-mation on the sample in general. Our expe-rience after approximately two years is that the 1D/2D system is a rugged and reliable system for routine 1D analysis and that it is easily switched to 2D mode when additional separation power is needed. The GERSTEL MAESTRO software provides easy and con-venient set-up by mouse-click of the entire system from one integrated method and one integrated sequence table.

Peak Area1 Twister 1,535,4035 Twisters 8,587,702


Direct injection for gas chromatographic profiling of alcoholic beverages is usually

preferable, but when these contain significant amounts of non-volatile material, pre-treat-ment is typically required to avoid both inlet and column contamination. This consider-ation applies in particular to products aged for extended periods in wooden barrels and especially products containing added sugar, as volatile artifacts from sugar decomposition in the hot injection port can also complicate the chromatogram. In this paper a combination of static and dynamic headspace analysis is described for routine profiling of both abun-dant and trace compounds in alcoholic bever-ages containing dry extract. Both techniques are performed using one combined analyti-cal instrument and for both techniques the only sample preparation required is dilution of the sample in a headspace vial.

Introduction

Commercial distilled spirits are complex mix-tures of flavor compounds in a dominant eth-anol-water matrix [1,2]. These compounds originate from the combined production pro-cesses of raw material extraction, fermenta-tion, distillation, and in many cases, ageing in oak barrels. Except for some low volatil-ity compounds originating from wood lignin breakdown during ageing, the majority of fla-vor compounds in distilled spirits are ame-nable to gas chromatographic analysis. The matrix composition of distilled spirits is rel-atively clean and so direct injection without time-consuming sample preparation is possi-ble. Abundant compounds at high mg/L lev-els can be quantified by simple split injection with flame ionization detection [3,4]. Addi-tional compounds at low mg/L levels (higher esters and acids) can also be assayed by direct injection of 5-10 µL using a PTV injector for both removal of solvent and enrichment of compounds in the liner. This can be extended to 50-100 µL injections for even lower detec-tion limits, but in this case sample introduc-tion must avoid overloading of the injection port liner and subsequent sample loss through the split vent. Speed programmed injection is necessary and recoveries depend on com-plex interactions between many related sam-ple and instrumental parameters [5]. How-

Efficient flavor profiling of beverages that contain involatile matrix

See the big picture - and every little detail


ever, there are many commercial alcoholic beverages which can contain relatively sub-stantial amounts of non-volatile material, and for which direct injection techniques may not be suitable. Fruit spirits and liquors can con-tain high amounts of added sugar, and very old brandies and whiskies etc. may contain higher than usual amounts of polyphenolic material from wood ageing.

Without frequent liner exchange non-volatile material will accumulate and contam-inate both inlet system and column. Added sugar in such products also degrades in the hot inlet to produce artifacts which complicates chromatograms. In these cases there are addi-tional techniques available which can avoid the unwanted effects of non-volatile mate-rial. These can be summarized as solid phase micro-extraction (SPME), stir bar sorptive extraction (SBSE) and headspace sorptive extraction (HSSE), static (HSS) and dynamic headspace sampling (DHS). All these tech-niques have many well documented applica-tions in the literature [6-11].

With SPME a choice of sorbent materials is available but only limited sorbent volumes can be accommodated on the fiber. SBSE and HSSE can use much greater volumes of sor-bent material, but this is almost always exclu-sively apolar polydimethylsiloxane. Head-space application could have the advantage that results may reflect more the actual sen-sory properties of the product analyzed. Static headspace with intermediate adsorbent trap-ping was applied to spirit drinks containing dry extract for analysis of the principal abun-dant secondary alcohols and esters [7]. Auto-mated dynamic headspace using replaceable adsorbent traps was used to profile volatile compounds in beer [12].

In this paper we describe the sequential application of static and dynamic headspace to profiling both abundant and trace compounds in an aged whiskey. Maximum sensitivity for each mode is achieved by using a PTV injector in solvent vent mode where the liner can also act as a cold trap. Use of a short 0.15 mm I.D. apolar capillary column with a phase ratio of 19 allows fast analysis with excellent separa-tion of both abundant and trace compounds. All operations for both modes of analysis are amenable to total automation for unattended sequence operation.

Figure 2. Schematic view of the DHS process.

Table 1. Compound identification.

No. Compound 1 Propanol

2 Ethyl acetate

3 Isobutanol

4 3-Methyl butanal

5 2-Methyl butanal

6 1-Butanol

7 1,1-Diethoxy methane

8 Propionic acid ethyl ester

9 n-Propyl acetate

10 3-Methyl-1-butanol

11 2-Methyl-1-butanol

12 Isobutyric acid ethyl ester

13 Isobutyl acetate

14 Butyric acid ethyl ester

15 Butyric acid 2&3-methyl-ethyl ester

16 Isobutyraldehyde diethyl acetate

17 Isoamyl acetate

18 2-Methyl-1-butyl acetate

19 Butyraldehyde diethyl acetal

20 Acetaldehyde ethyl amyl acetal

21 Hexanoic acid ethyl ester

22 Hexyl acetate

23 Heptanoic acid ethyl ester

24 Nonanal

25 ß-Phenyl ethyl alcohol

26 Octanoic acid

27 Octanoic acid ethyl ester

28 Decanal

29 ß-Phenyl ethyl acetate

30 Nonanoic acid ethyl ester

31 Decanoic acid

32 Ethyl trans-4 decenoate

33 Decanoic acid ethyl ester

34 Octanoic acid 3-methyl- butyl ester

35 1-Ethyl propyl octanoate

36 Capric acid isobutyl ester

37 Dodecanoic acid

38 Decanoic acid ethyl ester

39 Pentadecanoic acid 3-methyl-butyl ester

40 Pentadecanoic acid 2-methyl-butyl ester

41 Tetradecanoic acid ethyl ester

42 Ethyl-9-hexadecenoate

43 Hexadecanoic acid ethyl ester

Figure 1. GERSTEL MPS 2 with DHS mounted on an Agilent Technologies 7890 GC.

Figure 3. Static headspace chromatogram of an aged whiskey, a listing of compounds is shown in table 1.

Figure 4. Dynamic headspace chromatogram of an aged whiskey, a listing of compounds is shown in table 1.

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REFERENCES

[1] Aroma of Beer, Wine and Distilled Bev-erages, L. Nykänen, H. Suomalainen, Eds. Akademie-Verlag. Berlin (1983).[2] R. de Rijke, R. ter Heide, in Flavour of Distilled Beverages; J. Piggott Ed.; Ellis Hor-wood: Chichester (1983) 192.[3] K. Mac Namara, J. High Res. Chrom. 7 (1984) 641[4] R. Madera, B. Suárez Valles, J. Chrom. Sci. 45 (2007) 428[5] J. Staniewski, J. Rijks, J. Chrom. A 623 (1992) 105-113[6] A. Zalacain, J. Marín, G.L. Alonso, M.R. Salinas, Talanta 71 (2007)[7] K. Schulz, J. Dressler, E-M. Sohnius, D.W. Lachenmeier, J. Chrom. A 1145 (2007) 204-209.[8] J.C.R. Demyttenaere, J.L. Sánchez Mar-tínez, M.J. Téllez Valdés, R. Verhé, P. San-dra, Proceedings of the 25th ISCC, Riva del Garda, Italy, (2002).[9] P. Salvadeo, R. Boggia, F. Evangelisti, P. Zunin, Food Chem., 105 (2007) 1228[10] B. Tienpont, F. David, C. Bicchi, P. San-dra, J. Microcol. Sep. 12(11) 577-584 (2002)[11] C. Bicchi, C. Cordero, E. Liberto, P. Rubiolo, B. Sgorbini, P. Sandra, J. Chrom. A 1071 (2005) 111- 118.[12] J.R. Stuff, J.A. Whitecavage, A. Hoff-mann, Gerstel Application Note AN/2008/4

are very reproducible and do not normally require use of internal standards.

Conclusion

A combination of static and dynamic head-space techniques offers a useful complimen-tary approach for profiling major and minor components in alcoholic beverages, especially those with substantial levels of dissolved sol-ids. All constituent parts of each analysis are automated using the described instrumen-tation and no off-line sample preparation is required.

Aqueous and high water content samples can often be problematic for headspace analysis. The presence of water vapor in the headspace above the sample can lead to poor precision. Operating the PTV inlet in solvent vent mode using a Tenax-filled liner significantly reduces the amount of water transferred to the ana-lytical column.

The GERSTEL Dynamic Headspace System (DHS) is an option for the Mul-tiPurpose Sampler (MPS) which enables dynamic purging of the headspace above a sample. Analytes in the purged headspace are trapped onto a 2 cm sorbent bed in a com-pact glass tube, an optional dry purge step allows reduction of water content. The ther-mal desorption tube is then placed into the Thermal Desorption Unit (TDU) and ther-mally desorbed into the pre-cooled CIS 4 inlet, where the analytes are cryofocused to improve peak shape before introduction into the column. Applying the solvent vent mode in the TDU before transfer of analytes to the CIS provides an additional venting step of e.g. fusel alcohols. Figure 2 shows a schematic of the trapping and desorption process.Sample Preparation. No sample preparation other than transferring the samples into empty 10 mL screw cap headspace vials is necessary.

Results and discussion

Figure 3 shows a typical trace obtained using the headspace approach. The fusel or higher alcohols together with ethyl acetate and the principal straight chain fatty acid esters up to dodecanoic acid ethyl ester dominate the chromatogram. Interesting also in the initial elution space are clear peaks for important trace aldehydes, ethyl esters and acetals. Of particular importance are the ethyl esters of short chain fatty acids, called fruit esters due to their pleasant aromas. Pungent aldehydes and their sweet acetals with various alcohols can also affect perceived aroma.

Figure 4 in turn shows the chromatogram obtained when the same sample is injected after dynamic headspace stripping. Analytes up to the C5 alcohols have been partially vented in the TDU since their elution in the chromatogram would give only limited infor-mation due to chromatographic crowding, but now much more compound detail is apparent in the remaining elution space. Many interest-ing esters of both straight and branched chain higher esters are visible and it is even possible to profile some acids. Nonanal and Decanal have been reported previously in beer, wine and cognac, and both are used in the flavor and fragrance business. Both injection modes

Experimental

Analyses were performed using a 7890 GC equipped with a 5975 Mass Selective Detec-tor (Agilent Technologies), Thermal Desorp-tion Unit (TDU, GERSTEL), PTV inlet (CIS 4, GERSTEL) and MPS 2 with head-space and DHS option (GERSTEL) as shown in figure 1.

Analysis conditions static headspace

Trap: Tenax TA MPS: 60°C incubation temperature (10 min) 2.5 mL injection volume

Analysis conditions dynamic headspace DHS

Trap: Tenax TADHS: 30°C trap temperature 60°C incubation temperature (10 min) 50 mL purge volume 10 mL/min purge flow 10 mL dry volume 5 mL/min dry flowTDU: solvent venting 20°C (1 min); 720°C/min; 110°C (1 min); 720°C/min; 300°C (3 min)

Analysis conditions Cooled Injection System (CIS 4)

CIS: Tenax TA liner, solvent vent (60 mL/min) at 0 kPa. Splitless (2 min) 20°C (0.2 min); 10°C/s; 300°C (5 min)Column: 25 m CP-SIL 5CB (Varian) di = 0.15 mm df = 2.0 µmPneumatics: He, constant flow = 0.5 mL/minOven: 40°C (10 min); 10°C/min; 300°C (6 min)MSD: Scan, 28 - 350 amu

Authors

Kevin Mac Namara, Frank McGuiganIrish Distillers-Pernod Ricard, Midleton Distillery, Midleton, Cork, Ireland

Andreas HoffmannGERSTEL GmbH & Co. KG, Eberhard-Ger-stel-Platz 1, 45473 Mülheim an der Ruhr, Germany


Food Safety

So long, troublemakers I

The QuEChERS method may be a recent arrival on the scene, but it is conquering the world. QuEChERS provides fast and reasonably priced extraction, enabling efficient determination of pesticide levels in agricultural samples. GERSTEL application chemists have used automated Disposable Pipette Extraction (DPX), a miniaturized dispersive SPE technique, combined with GC/MS to optimize the determination of pesticides in QuEChERS extracts. Interfering

matrix compounds can be chased off quite easily - without laborious sample preparation.

Pesticides have long helped provide ample, affordable, and safe food supplies for bil-

lions of people across the globe. Even so, con-stant vigilance is needed in order to protect the environment and consumers from the consequences of improper application of pes-ticides to plants and crops. When it comes to food safety, the necessary first step is always to find efficient ways of controlling the quality of our food on a large scale in our globalized economy. Just the pesticides that can legally be used represent a list of hundreds of com-pounds with widely different characteristics. Multimethods are required, spanning both liquid chro-matography (HPLC) and gas chromatography (GC) combined with Mass Spec-trometry (MS). In theory, the analytical chemist can track down pretty much every pes-ticide known to man. In prac-tice, the right sample prepara-tion is critical if one wants to achieve accurate results; and it had better be automated, we’re talking about a big job.

In just a few years, the QuEChERS method (Quick, Easy, Cheap, Efficient, Rug-ged, and Safe) has become the method of choice for extracting toxins from a variety of foods. Initial ly, QuEChERS was

QuEChERS extracts the analytes – and more...

Every solution results in new, unexpected and interesting challenges and there is a price to pay for going QuEChERS: Fruit and vegetable extracts produced using the QuEChERS method contain large amounts of matrix residue. But „quick and dirty“ is fine if we can get rid of the dirt after-wards. There are two ways to accomplish this: Clean up the extract or use analytical instruments that can handle samples with

matrix residue. If we take a separate look at each of these alternatives, fur-ther clean-up of QuEChERS extracts is

typically performed using manual dispersive solid phase extraction (SPE) fol-lowed by centrifugation to remove solids. These steps are not easily automated, but the same clean-up ef-fect can be accomplished using Disposable Pipette Extraction (DPX), a dis-persive SPE technique that is fully automated. In this article, examples are pre-sented, which show that

The GERSTEL MultiPurpose Sampler (MPS) PrepStation enables combined DPX extraction and sample introduction to the GC.

developed as a fast and inexpensive method to extract pesticides from various, mainly plant-based matrices. Validation studies have proven that the QuEChERS method results in good recovery and low standard deviation for a wide range of pesticides. Furthermore, the QuEChERS method is much less labor-intensive and requires much less solvent than previously used methods. A wide range of pes-ticides can be extracted. In many laboratories, QuEChERS has caused a veritable produc-tivity boom.


Schematic diagram of the DPX clean-up.Spinach and orange extracts before and after DPX clean-up.

Spinach extract Orange extract

withoutclean-up

clean-up with

DPX-Qg

withoutclean-up

clean-up with

DPX-Q

clean-up with

DPX-Qg

DPX is an attractive and efficient alternative for clean-up of spinach and orange extracts. Should the analyst not want to perform fur-ther clean-up of such extracts prior to GC/MS analysis, the only remedy is to replace the GC inlet liner at regular intervals. Liner exchange is normally a time-consuming

task, but GERSTEL‘s Automated Liner EXchange (ALEX) performs Liner EX-change automatically, enabling the analysis of samples with undissolved sample matrix. Matrix build-up has negative consequences especially for the GC/MS system: If raw QuEChERS extracts are injected directly into the GC, residue will accumulate in the

inlet. This build-up will lead to compound loss by adsorption on active surfaces and increased variability, negatively impacting the re-sults. In combination with the MultiPur-pose Sampler (MPS), ALEX performs auto-mated liner exchange at user-defined intervals.

Disposable Pipette Extraction (DPX DPX is an SPE tech-nique that relies not on packed adsorbents in standard cartridges, but on adsorbent pow-der placed inside dis-posable pipette tips. In the case of spinach and orange extracts, graphitized Carbon Black was used among other adsorbents (DPX Qg-tips, as specified in DIN EN 15662). Plant colorants, such as chlorophyll, and free acids were successfully removed. The transport adapter at the top and a frit at the bottom help contain adsorbent and sample inside the pi-pette tip while enabling highly efficient air-bubble induced mixing.

The transport adapter also serves the dual purpose of allowing the MPS to get a grip on the cartridge in order to transport it and to introduce the syringe needle into the car-tridge for liquid transfer. The DPX process is clever yet simple: The MPS picks up a DPX tip from the tray. Depending on the method, the adsorbent can be washed with a suitable solvent, which is taken from a solvent reser-voir. The solvent can either be aspirated into the tip from below or added to the top using the autosampler syringe. A 500 µL sample of the extract in question was aspirated into the tip. Extracts had been spiked with organo-chlorine- and organophosphorous pesticide standard mixtures at different concentra-tion levels. Samples were aspirated into the DPX tip from below, which means they were never in contact with the syringe needle or piston. „There is no sample-to-sample cross contamination or carry-over“ said Carlos Gil, Manager, Analytical Services at GER-STEL Headquarters, while adding: „Since DPX is a dispersive SPE technique, the ex-traction efficiency is not influenced by the flow path or the flow rate through the adsor-bent, making the technique highly rugged and reliable“. Once the sample has entered the DPX tip, the syringe pulls air through the tip and the sample from below. The liq-uid suspension undergoes highly efficient turbulent mixing leading to optimal contact between the phases and highly efficient and fast extraction. „The efficiency of the clean-up is clearly demonstrated by the fact that the final spinach extract is almost completely colorless“, says Carlos Gil. The extraction takes place in less than two minutes. Then the cleaned QuEChERS extract is then transferred directly to a clean autosampler vial for analysis or to undergo further liquid sample preparation steps prior to the analysis as needed. The used pipette tip is discarded. As soon as the prepared sample has been in-troduced to the GC system, a clean pipette tip is picked up and the next sample pre-pared. „Analysis and sample preparation are performed in parallel, ensuring best possible utilization and return on investment for the entire instrument set-up“, says Carlos Gil.

Full scan chromatograms of the spinach extract before (A) and after (B) DPX clean-up.

SIM chromatogram after DPX clean-up of spinach extract spiked to a concentration of 200 ppb with a standard pesticide mixture.


Method parametersThe analysis was performed on a GC 7890 / MSD 5975C GC/MS system (Agilent Technologies) configured with a GERSTEL Cooled Injection System (CIS) PTV-type inlet and a GERSTEL MultiPurpose Sampler (MPS) sample preparation robot fitted with a 10 µL syringe for liquid injection.

Analysis parameters CIS 4: splitless 25 °C; 12 °C/s; 280 °C (3 min)Column: 30 m DB5-MS (Agilent) di = 0.25 mm; df = 0.25 µmCarrier gas: He, constant flow 1.0 mL/minGC oven: 60 °C (1 min); 10 °C/min; 300 °C (3 min)

StandardsA standard mixture of organochlorine- and organophospho-rous pesticides at a concentration of 1000 µg/L was prepared in Acetonitrile.

Sample preparationFor quantification purposes, fruit and vegetable extracts were spiked with diluted pesticide standards. (Concentrations: 20 µg/L and 200 µg/L in 500 µL extract).

DPX extraction1 mL QuEChERS tips from DPX-Labs, LLC. 500 µL of the fruit- or vegetable extract was automatically transferred to a vial by the MPS fitted with a 2.5 mL syringe. A 1 µL aliquot of the extract was introduced to the GC.

More information

http://www.gerstel.de/pdf/p-gc-an-2009-01.pdf

The sequence table for automated DPX sample preparation is easily and quickly set up by mouse-click in the MAESTRO.

Percent recovery and relative standard deviation for the pesticides.

Recovery of the pesticides with and without DPX clean-up (spiked to a concentration level of 200 ppb).

Orange Spinach

Analyte % Recovery % RSD % Recovery % RSD

20 ppb 200 ppb 20 ppb 200 ppb 20 ppb 200 ppb 20 ppb 200 ppb

Dichlorvos 139 80 14 15 92 51 8.3 15Mevinphos 89 68 15 10 60 34 8.3 15Phorate 68 122 16 3.7 16 93 32 5.2α-BHC 100 113 5.9 4.4 47 76 16 6.2δ-BHC 126 89 6.3 8.2 105 51 17 24Diazinon 151 116 5.1 4.4 117 96 2.5 3.9Methyl Parathion 263 104 7.9 12 165 54 20 14Ronnel 97 75 5.5 5.8 95 63 11 9.8Aldrin 173 138 5.2 3.4 148 124 1.9 3.3Trichloronate 119 74 26 3.6 152 87 8.3 6.8Heptachlor Epoxide 142 135 4.3 3.0 120 102 4.2 3.4t-Chlordane 147 140 4.9 2.7 135 116 3.7 3.5Prothiofos 131 98 1.9 4.0 162 104 4.7 6.3Dieldrin 168 137 5.2 2.4 128 123 9.0 3.2Endrin 167 149 6.5 4.0 142 118 5.4 3.9β-Endosulfan 156 134 4.7 2.9 138 102 12 7.4Fensulfothion 121 142 6.9 5.1 63 88 4.6 11Sulprofos 196 136 3.6 4.3 200 122 4.3 6.4DDT 213 179 4.5 11 208 117 6.9 7.3Endrin Keton 174 144 2.6 3.8 138 97 2.1 7.7Average 147 119 7.6 5.7 122 91 9.1 8.2

Analyte Orange Spinach

No DPX DPX No DPX DPX

Dichlorvos 128 80 120 51Mevinphos 179 68 145 34Phorate 180 122 170 93α-BHC 158 113 150 76δ-BHC 213 89 170 51Diazinon 162 116 160 96Methyl Parathion 483 104 300 54Ronnel 196 75 195 63Aldrin 204 138 210 124Trichloronate 242 74 245 87Heptachlor Epoxide 198 135 155 102t-Chlordane 167 140 175 116Prothiofos 257 98 265 104Dieldrin 198 137 260 123Endrin 197 149 195 118β-Endosulfan 192 134 180 102Fensulfothion 197 142 165 88Sulprofos 246 136 250 122DDT 224 179 195 117Endrin Ketone 168 144 155 97Average 209 119 193 91

The power of DPX - conclusion

Apart from the visible removal of spinach and orange matrix, the analysis results bear testament to the efficiency of the DPX pro-cess. Carlos Gil: „The results were convincing, we had excellent recovery of the organochlorine- and organophosphorous pesti-cides that were determined in the study“. The relative standard deviation (n=3) was under 10 % both for the extract spiked at 20 ppb and for the extract spiked at 200 ppb. Average recoveries were 119 % for the orange sample and 91 % for the spinach. The study proved that automated DPX is useful for second stage clean-up of QuEChERS extracts prior to GC/MS analysis. The DPX tips efficiently removed interfering matrix material, improving over-all system reliability and productivity, and reducing the need for maintenance since there was less residue build-up in the GC/MS system.


The QuEChERS (quick, easy, cheap, effective, rugged, and

safe) sample extraction method offers food safety laboratories a novel method that is a genuine step forward. QuEChERS is now the basis for efficient mon-itoring of pesticides in an ever-growing range of foods. Still, the method is quite labor intensive with several manual steps such as shak-ing, centrifugation, and dispersive SPE. If the dispersive SPE clean-up step could be automated, laboratory produc-tivity could be improved significantly. When using the automated QuEChERS clean-up procedure for challenging botanical samples, it can be difficult to reach the low limits of detection required in order to meet acceptance criteria for reporting the maximum residue levels (MRLs) as established by regulatory agencies. Automated QuEChERS clean-up of fruit and vegetable extracts combined with LC-MS/MS determination of pesticides has been reported previously. This study focuses on using a similar system to automate the sec-ond step of the QuEChERS procedure and introduce the cleaned extract directly to an LC-MS/MS system. The aim is to provide high throughput analysis for the confirma-tion of pesticide residues in botanical matri-ces. Automated QuEChERS extractions are performed using a QuEChERS dispersive SPE sorbent blend for fatty matrices.

Experimental

Stock solutions containing the pesticide com-pounds listed in Table 1 in acetonitrile were

Automated QuEChERS extract clean-up for LC-MS/MS

So long, troublemakers IILC/MS and GC/MS systems are increasingly confronted with QuEChERS extracts that have to be cleaned prior to determination of pesticide residues in order to avoid build-up of matrix residue in the analysis system. Automated QuEChERS extract clean-up, including vortexing, centrifugation, and filtration directly followed by LC-MS/MS analysis

of the cleaned extract is demonstrated in this article.

prepared and provided by the FDA. Calibration standards and matrix matched standards were prepared by making appropriate dilutions of the pesti-cide stock solutions using mobile phase, blank hop extract, or blank ginseng extract result-ing in the following concentrations: 0.5, 1, 2, 5, 10, 20, 50, 100, 200, 500, and 1000 ng/mL. Crude acetonitrile extracts of pesticide-for-tified samples, incurred samples, and blank matrix samples based on both hops and gin-seng root were prepared and provided by the FDA. These samples were generated using QuEChERS extraction salts for the DIN EN 15662 Method and the recommended sample preparation method supplied with the salts. All automated PrepSequences were per-formed using a MultiPurpose Sampler (MPS XL Dual Head) configured for QuEChERS-LC-MS/MS analysis.

QuEChERS extract pretreatment:• Pipette 1 mL of the acetonitrile extract

obtained following the 1st centrifugation step of the QuEChERS sample prepara-tion method into a 2 mL glass autosampler vial containing a sorbent from a dispersive SPE kit for fatty samples, AOAC.

• Place the sample onto a tray on the GER-STEL MPS XL Dual Head.

Automated Q uEC hERS extract clean-up:• Agitate the sample vial for 1 minute using the Anatune CF-100 centrifuge.• Centrifuge the sample vial at 575 g for 3 minutes using the Anatune CF-100 centrifuge.• Filter 500 µL of the result-ing supernatant through a 0.45 µm GERSTEL format syringe filter.

• Combine 100 µL of the resulting filtrate with 400 µL of mobile phase A in a clean 2 mL vial.

• Agitate the sample vial using the Anatune CF-100 centrifuge for 30 seconds.

Inject 2 µL into the LC-MS/MS system.

Analysis conditions LC

Mobile Phase: A - 5 mM ammonium formate in water with 0.01 % formic acid B – 0.01 % formic acid in acetonitrileGradient: Initial 94 % A / 6 % B0.3 min 94 % A / 6 % B14 min 5 % A / 95 % B17 min 5 % A / 95 % BPressure: 600 barFlowrate: 500 µL/minRuntime: 17 minPost time: 2.5 minColumn: 2.1 mm x 100 mm, 1.8 µm,Zorbax Eclipse+ C18 RRHT (Agilent)Oven: 55°CInjection volume: 2 µL

Analysis conditions MS

Operation: ESI+ mode ( Jet Stream)Time Filter Width: 0.04 minScan Type: Dynamic MRMDelta EMV: 0 VCycle Time: 660 msGas Temperature: 225 °CGas Flow (N2): 10 L/minNebulizer pressure: 25 psiSheath Gas (N2): 350 °C11 L/minCapillary voltage: 4500 VNozzle Voltage: 500 V

Figure 1. Representative Mass Chromatograms for low QC sample.

Figure 5. shows a representative calibration curve resulting from automated preparation of neat stan-dards. The calibration curves were shown to be lin-ear from at least 1.00 to 200 ppb for the pesticides monitored, using a linear, 1/x regression method.


Authors

Fred Foster & Virgil Settle · GERSTEL, Inc., Linthicum, MD U.S.A. · Paul Rob-erts, Anatune, Ltd., Cambridge, UK · Peter Stone, Agilent Technologies, Santa Clara,CA, U.S.A. · Joan Stevens, Agilent Technologies, Wilmington, DE, U.S.A. · Jon Wong, Kai Zhang, US FDA, College Park, MD, U.S.A

Preparation of all standards was automated using the MPS XL Dual Head as follows:• Transfer 100 µL of previously extracted matrix blank or 100 %

acetonitrile to an empty 2 mL autosampler vial.• Transfer 250 µL of mobile phase A to the vial.• Transfer 150 µL of the respective standard stock solution to

the vial.• Agitate the vial using the Anatune CF-100 and centrifuge for

30 seconds.

All analyses were performed using an Agilent 1290 HPLC, an Agilent 6460 Triple Quadrupole Mass Spectrometer with elec-trospray source and Jet Stream Option and a GERSTEL MPS XL autosampler configured with Active Wash Station. Sample injections were made using a 6 port (0.25 mm) Cheminert C2V injection valve fitted with a 2 µL stainless steel sample loop. The mass spectrometer acquisition parameters and respective quanti-fier/qualifier ion transitions were chosen using the pesticide data-base option available for the MassHunter B.03.01 software. Table 1 provides a list of the more than 200 pesticides that were monitored using this single LC-MS/MS method. A retention time window value of 0.5 minute was used for each positive ion transition being monitored during the course of the dynamic MRM experiment.

Results and discussion

Figures 1 - 4 show representative overlay mass chromatograms resulting from QuEChERS extracts of pesticide-fortified sam-ples. More than 200 different pesticides were successfully deter-mined in botanical matrices using the automated QuEChERS-LC-MS/MS method.

The total time required per sample to perform the QuECh-ERS extract clean-up was 15 minutes. This was shorter than the LC-MS/MS analysis run, enabling the MPS system to complete preparation of the next sample during the LC-MS/MS run for maximum sample throughput.

Conclusion

The study has demonstrated: • Successful monitoring of more than 200 pesticides in

botanical matrix samples using automated QuEChERS extract clean-up coupled with LC-MS/MS analysis using the Agilent 6460 Triple Quadrapole Mass Spectrometer.

• Automation of both the QuEChERS extract clean-up and the preparation of standards using the GERSTEL MPS XL Dual Head robotic sampler.

• The “just-in-time” sample preparation capability included in the MAESTRO software enables highly efficient QuEChERS extract clean-up and analysis.

3-Hydroxycarbofuran Acephate Acetamiprid Acibenzolar-S-methyl Alanycarb Aldicarb Aldicarbsulfone Aldicarb sulfoxid Aspon Avermectin B1a Avermectin B1b Azadirachtin Azoxystrobin Benalaxyl Bendiocarb Benfuracarb Benoxacor Benthiavalicarb Benzoximate Bifenazate Bifenthrin Bitertanol Boscalid Bromuconazole-1 Bromuconazole-2 Bupirimate Buprofezin Butafenacil Butocarboxym Butoxycarboxim Cadusafos Carbaryl Carbendazim Carbetamid Carbofuran Carboxine Carfentrazone-ethyl Chlordimeform Chlorfenvinphos-beta Chlorfluazuron Chlorotoluron Chloroxuron Clethodim Clofentezine Clothianidin Coumaphos Cumyluron Cyanazine Cyanophos Cyazofamid Cycluron Cymoxanil Cyproconazole Cyprodinil Cyromazine d10-Diazinon d6-Dichlorvos d6-Dimethoate d6-Diuron d6-Linuron d6-Malathion Daimuron Dazomet Deltamethrin Diazinon Dichlorvos Dicrotophos Diethofencarb Difenoconazol Diflubenzuron Dimethenamid Dimethoat Dimethomorph A Dimethomorph B Dimoxystrobin Diniconazole Dinotefuran Dioxacarb Disulfoton Dithiopyr Diuron Dodemorph 1 Dodemorph 2 E-Fenpyroximate Emamectin B1a Emamectin B1b Epoxiconazole Eprinomectin B1a EPTC Esprocarb Ethidimuron Ethiofencarb Ethion Ethiprole Ethirimol Ethofumesate Ethoprop Etobenzanid Etofenprox Etoxazole Famoxadone Fenamidone Fenarimol Fenazaquin Fenbuconazol Fenhexamid Fenoxanil Fenoxycarb Fenpropathrin Fenpropimorph Fenuron Flonicamid Flucarbazone Fludioxinil Flufenacet Flufenoxuron Flumetsulam Flumioxazin Fluometuron Fluquinconazole Flusilazol Fluthiacet-methyl Flutolanil Flutriafol Forchlorfenuron Formetanate Fuberidazole Furalaxyl Furathiocarb Heptenophos Hexaconazol Hexafl umuron Hexythiazox Hydramethylnon Imazalil Imazapyr Imibenconazole Imidacloprid Indanofan Indoxacarb Ipconazole Iprovalicarb Isocarbamid Isofenfos Isopropalin Isoproturon Isoxaben Isoxafl utole Kresoxim-methyl Lactofen Leptophos Linuron Lufenuron Mandipropamid Mefenazet Mepanipyrim Mepronil Metalaxyl Metconazole Methabenzthiazuron Methamidophos Methiocarb Methomyl Methoprotryne Methoxifenozid Metobromuron Metribuzin Mevinphos Mexacarbate Molinate Monocrotophos Monolinuron Moxidectin Myclobutanil Neburon Nitenpyram Norflurazon Novaluron Nuarimol Omethoate Oxadixyl Oxamyl Paclobutrazol Penconazole Pencycuron Phenmedipham Picoxystrobin Piperonyl butoxide Pirimicarb Prochloraz Promecarb Prometon Prometryn Propachlor Propamocarb Propargite Propazine Propham Propiconazole Propoxur Pymetrozine Pyracarbolid Pyraclostrobin Pyridaben Pyrimethanil Pyriproxyfen Quinoxyfen Rotenone Sebuthylazine Secbumeton Siduron Simazine Simetryn Spinosyn A Spinosyn D Spirodiclofen Spiromesifen Spiroxamin Sulfentrazone Tebuconazole Tebufenozide Tebufenpyrad Tebuthiuron Tefl ubenzuron Temephos Terbumeton Terbutryn Terbutylazine Tetraconazole Tetramethrin cis Thiabendazole Thiacloprid Thiametoxam Thiazopyr Thidiazuron Thiobencarb Thiofanox Thiophanate-methyl Triadimefon Triadimenol Trichlamide Trichlorfon Tricyclazole Trifloxystrobin Triflumizole

Further Information

http://www.gerstel.com/pdf/p-lc-an-2010-04.pdf

Figures 2 through 4 show representative overlay mass chromatograms of neat, hop matrix matched, and gin-seng matrix matched calibration standards respectively at 10 ppb. The standards were prepared automatically by the MPS XL.

Figure 3. Representative overlay mass chromato-gram for a 10 ppb hop matrix matched standard.

Figure 4. Representative overlay mass chromatogram for a 10 ppb ginseng matrix matched standard.

Table 1. 200+ pesticides monitored using automated QuEChERS extract clean-up.


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Novel automated Pyrolyzer for the GERSTEL TDU

Pyrolyzer module for the GERSTEL Thermal Desorption Unit (TDU) enables highly flexible and efficient automated pyrolysis of

solids and liquids at up to 1000 °C.

GERSTEL has further expanded the capa-bilities of the Thermal Desorption Unit

(TDU) adding a new dimension to an already vast range of technologies supported by our compact thermal desorber. A cleverly designed pyrolysis accessory enables efficient and flex-ible automated pyrolysis of liquids and solids. If required, thermal desorption and pyroly-sis of the same sample can be performed in sequence to obtain the maximum amount of information in the shortest possible time. Different sample holders and different pyrol-ysis and GC/MS methods can be used in one automated sequence for faster and simpler method development and the analyst can run a range of different sample types in one auto-mated sequence. When combined with the GERSTEL MultiPurpose Sampler (MPS), up to 196 samples can be analyzed automatically in one batch. With just one method and one sequence table the analyst can set up the complete system includ-ing thermal desorption, pyrolysis, and the GC/MS runs. This reduces the risk of error and enables a highly efficient work-flow, while providing sensitive and reliable results. The initial thermal desorption can be performed at temperatures ranging from ambient to 350 °C. Pyrolysis is per-formed at temperatures from 350 °C to 1000 ° C.

The temperature program can be varied from sample to sample. Heating rates range from 0.02 °C/s to 100 °C/s, which means that optimal analysis conditions can be cho-sen for each sample type and for every con-ceivable matrix. Slow heating can, for example, be used for TGA simulation. Pyrolysis break-down products are transferred to the GC/MS system using the GERSTEL Cooled Injection System (CIS) PTV-type inlet. The CIS can be used either simply as a heated split inter-face or as an intermediate cryofocusing trap in order to focus volatile analytes for best possi-ble separation and maximum information content. The valve-free liner-in-liner concept eliminates sample-to-sample carry-over and the TDU and CIS liners are heated over their entire lengths to ensure best possible recov-

ery and minimal contami-nation. The platinum fila-ment is connected at four different points providing extremely accurate tem-perature control as well as monitoring of the filament condition, thus ensuring reliable results at all times. Change over between stan-dard TDU operation and pyrolysis operation is per-formed in less than ten minutes ensuring that the complete system including the GC/MS can be used flexibly and to the great-est possible benefit of the laboratory.

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GERSTEL online: Information on products, applications, events and downloads, as well as general information about GERSTEL and our customer focused solutions: www.gerstel.com and www.gerstelus.com.

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Published byGERSTEL GmbH & Co. KG Eberhard-Gerstel-Platz 1 45473 Mülheim an der Ruhr, Germany

Editorial directorGuido Deussing Uhlandstrasse 16 41464 Neuss, Germany [email protected]

Scientific advisory boardDr. Eike Kleine-Benne [email protected] Dr. Oliver Lerch [email protected] Dr. Malte Reimold [email protected]

Translation and editingKaj Petersen [email protected]

DesignPaura Design, Hagen, Germany www.paura.de

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From the Mountains to the Ocean - · PDF fileGERSTEL BRASIL +55 11 5665 8931 [email protected] GERSTEL GmbH & Co KG Mülheim an der Ruhr, Eberhard-Gerstel-Platz 1 45473 Mülheim