GC BASIC

Contents

Basic Theory Configuration Carrier gas Injection port Column Detector

Flow Chart for Analysis

Sample collection Sample collection

PreparationPreparation

InjectionInjection SeparationSeparation DetectionDetection

IntegrationIntegration

ReportReport

Chromatography

LCSFCGC

LSC LLC

Column TLC

LSCAbsorption

IECIon exchange

SEC LLCPartition

BPCPartition

ICIon exchange

GPCSize exclusion

GFC IPCIon pairing

GSCAbsorption

GLCPartition

GC or LC

Advantages of GC

Fast Analysis Time High Resolution High Sensitivity Easy interface with MSD, AED Reproducibility Small injection volume Economic price

Analysis Flow of GC

System Configuration

Carrier Gas

Injection port

Column

Detector

Data system

Carrier Gas

Carrier Gas

Used for carrying vaporized sample to the column

Necessities : Inert, pure, dry Type : H2, N2, He, Ar

→ Different depending on detector

Recommended Carrier Gas

Best sensitivityN2

Best sensitivityN2ECD

Best Linear Dynamic rangeAr/CH4

Generally usedN2FID

Can be usedH2,He

Optimum HeNPD

Only use HeHePDD

Used for analysis of H2 N2

High sensitivity H2

General

Detector

N2IRD

MSD Mass Range 10-800 m/z

Must use HeHeMSD

Generally used He

TCD

Special

Detector

RemarkCarrier GasDetector

A : Moisture trap B : Hydrocarbon trap

C : Indicating Oxygen trap

Injection Port

Injection Port

Purpose - Vaporize sample - Transfer sample to the column

with accuracy and reproducibility

Sample type - Liquid or Gas

Injection Port

Injection port for packed column

Injection port for capillary column- Split

- Splitless

- Cool On Column

Sample preparation System - Headspace, Purge & Trap, Valve, Pyrolyzer etc.

Columns for Injection port

Packed Injection port - Packed column

- Wide bore capillary column(0.53 mm I.D.)

Capillary Injection port - Capillary column(0.25 ~ 0.53mm I.D.)

Packed Injection Port

Traditional sample injection method High resolution is not necessary Gas analysis using GSC(gas-solid chromatography) Simple design, Whole carrier gas transfer to the column Sample is transferred to the column after vaporization, the possibility of contamination from non volatile compounds is low

Packed Injection Port

Capillary Injection Port Split/Splitless

Split Injection

Developed for capillary GC Sample is vaporized at the injection port

by high temperature. Some part of sample

are transferred to the column and others

are vented Can be used in most of samples No limitation of solvent Good peak shape

Automated Pneumatic Control System (Split mode)

To Detector

Split Vent

Septum Purge

Carrier Gas

Flow Sensor FS

Pressure Sensor PS

Septum Purge Regulator

Trap

On/off valve V

Proportional Valve PV2

Proportional Valve PV1

Capillary inlet

High Flow Rate

Low Flow Rate

Split Ratio

Set up oven temperature Set up column pressure Set up septum purge flow

(3-5ml/min)

Set up split vent flow

Splitless injection port

All carrier gas goes to the column without venting

All sample is transferred to the

column after vaporizedThe sample is fully used into the

column : high sensitivity

high reproducibility

Automated Pneumatic Control System (Splitless mode)

To Detector

Carrier Gas

Flow Sensor FS

Pressure Sensor PS

Septum Purge Regulator

Trap

On/off valve V

Proportional Valve PV2

Proportional Valve PV1

Capillary inlet

Septum purge

Split Vent

Low Flow Rate

High Flow Rate

Splitless Injection

Have to optimize some conditions such as oven temperature comparing with split mode injection to reduce the band broadening

Can be used with high b.p solvent

Use with large capacity liner

Can be used with high column flow rate

Demerits of Splitless mode

Quantitation result depends on injection skill

Pay attention to select sample solvent

Possible to cause the column degradation rapidly

The component eluted at the tail of solvent peak depends on boiling point, polarity and injection volume of solvent

Optimizing analytical condition needed

Flow control for split/splitless

Length 0.25mm ID

0.32mm ID

0.53mm ID

15m30m60m105m

6psi12psi24psi40psi

4psi8psi

16psi30psi

1psi3psi6psi

10psi

Injector pressure set up

Split/splitless liner(I)

Have to use non activated Glass liner

if the sample has high activity Liner cleaning

- Rinse with MeOH/Acetone

- Do not use Acid and Base

- Do not use soap and detergent

Split/splitless liner(II)

Optimum injector condition

Standard Condition

- Injector temperature(general) : 250 ℃

- Volatile sample : 150 200∼ ℃ex) VOCs

- High b.p sample : 275-300℃ex) steroids, triglycerides or surfactants

Check the maximum temp. of septum installed

Contaminable parts of injector

Tubing used for carrier gas

Septum

Liner

Gold seal (split/splitless injector)

Contamination of septum

Contaminated septum After replace the septum

Oven temperature Setup

Compounds are onlyduplicated by Retention time

IsothermalTemperature

program

Yes No

Isothermal(a) and temperature program(b)

Isothermal condition setup Set up oven temperature

50 → 10 /min → Max. temperature of column ℃ ℃ Check the retention time and temperature of last

eluted compound Analyze sample at the below 20 of temperature for ℃

last eluted compound If the compounds are not separated, analyze again

on the decreased temperature Change the condition to the temperature program or

the column

Temperature program setup

1st step temperature program setup

50 → 10 /min → Max. temperature of column(30min)℃ ℃ After injection, check the chromatogram

Set up initial temperature and time

Set up increasing rate

Set up final temperature and time

Confirm optimum condition

Optimum oven temperature

Split injection mode

Splitless injection mode

(oven temp.: 25°~210°)

Splitless injection mode

(oven temp.:60°~210°)

Splitless injection

(Solvent : Methanol)

Column

Column

Separates the mixed compounds to individual components

Type

- Depending on I.D. : Packed, Capillary

- Depending on stationary phase : GSC, GLC

Packed / Capillary column

Packed column - Large inside diameter / short length - Large sample capacity - Low Resolution

Capillary column - Small inside diameter / long length - Small sample capacity - High Resolution

Comparison

Packed Capillary

Length (m)

ID (mm)

Flow rate (ml/min)

Pressure drop (psi)

Theoretical plate

Theoretical plate/length

Capacity

Film thickness (um)

1-6

2-4

10-60

10-40

5000(2m)

2500(2mm ID)

10ug

1-10

5-105

0.2-0.75

0.5-15

3-40

180000(60m)

3000(0.25mmID)

50ng(0.25mmID)

0.1-7.0

Packed Column

Traditional packing

..

Porous layer bead

Bead column

Capillary Column

Wall coated column

Chromatogram of plant extract

Packed column

Capillary column

Capillary column with high resolution

Van Deemter Curve

Optimum flow rate for carrier gas

Packed

Capillary

Column ID Optimum gas flow rate

Optimum gas linear velocity

1/4"1/8"

530 um (mega bore)320 um (wide bore)200 um (narrow bore)100 um (high speed)

50-60 ml/min20-30 ml/min

3-5 ml/min1-3 ml/min0.5-1 ml/min0.2-0.5 ml/min

2.6 - 3.2 cm/sec4.2 - 6.3 cm/sec

22 - 38 cm/sec20 - 62 cm/sec26 - 53 cm/sec42 - 106 cm/sec

Comparison of GSC / GLC

GSC GLC

Mobile Gas Gas phase

Stationary Porous polymer Solid support phase +Liquid phase

Separation Absorption/Desorption Partition

Gas Solid Chromatography

Carrier gas

Carrier gas

• Packed column

• Capillary column

packing material (GSC)

- Porous

- Large surface area

Gas Liquid Chromatography

Carrier gas

• Packed column

• Capillary columnSolid support :

Porous support

with large surface

area

Liquid phase

Capillary column selection

Sample type (Like dissolves likes)

Stationary phase type

Film thickness

Column Inside diameter

Column length

Column selection according to polarity

Polarity

• Non polar(HP-1, HP-5) : boiling point• Intermediate (HP-50+) : boiling point

hydrogen bond• Polar (HP-INNOWax, HP-Wax) :

interaction of functional group

Column selection guide

Non polar column

HP-1 (HP-101) - 100% Dimethylpolysiloxane - Phenol, Amines, Hydrocarbons, PCBs, Pesticides, Sulfur compounds - DB-1, BP-1, SPB-1, GB-1, CP-Sil 5, OV-1, SE-30

Non polar column

HP-5 - 5% Diphenyl / 95% dimethylpolysiloxane

- Fatty acid, Drugs, Methyl esters, Alkaloids,

Halogenated compounds

- DB-5, BP-5, SPB-5, CP-Sil 8, SE-52,

OV-5

Medium-polar column

HP-35 - 35% Diphenyl / 65% dimethylpolysiloxane

- Pesticides, Drugs, Amines

- DB-35, RTX-35, SPB-35, AT-35, Sup-Herb

Medium-polar column

HP-1701 - 14% Cyanopropylphenyl /

86% dimethylsiloxane

- Aroclors, Herbicides, Pesticides, TMS sugars

- DB-1701, SPB-1701, OV-1701, CP-Sil 19

Polar column

HP-FFAP - Acid modified Polyethylene glycol

- Acids, Alcohols, Aldehides, Nitriles,

Ketones

- DB-FFAP, OV-351, Stabilwax-DA

Chromatograms of gasoline by capillary column with varying on film thickness

Film thickness

Column ID 0.20mm 0.25mm 0.32mm 0.53mm 0.75mm

Sample

capacity(ng)5 - 30 50 - 100 400 - 500

1,000 -2,000

10,000 -15,000

Number of TP

(N/m)5000 4170 3330 1670 1170

Optimum

Flow rate

(He, 20cm/min)0.4 0.7 1.4 2.5 5

Column selection guide

Resolution according to length

Column length : Resolution : Retention time :

Column selection Guide

Select same polarity with sample Use the column ID 0.32mm

- Small ID(0.25mm) column : complex sample- Large ID(0.53mm) column : simple sample

Use the column length 30m - The higher resolution needed,the longer column you

select

Use the column 0.25 ㎛ film thickness- Thick film : volatile compounds- Thin film : non volatile compounds

Column cutting

Wrong column cutting

Right column cutting

Cutting tools

Installation method for column(at injector-side)

① Insert column nut to the column at first and

then insert ferrule.

② Keeping the column length 3 cm from the ferrule, insert the column to the adaptor and then hand-tighten the nut.

③ Loosen the column nut

④ Cut the column remaining 5 mm from the ferrule

⑤ Connect the column nut to the capillary adaptor again

⑥ Hand-tighten the nut and then tighten ¼ turn using wrench

Effect from wrong column connection

Ferrule Selection

Graphite(100%)

- ~450 ℃ - general, reusable

- FID, NPD, ECD

- can not be used for MSD

Vespel(100%)

- 280 ℃ - reusable

- for isothermal condition

Graphite/ vespel

- GC/MSD interface

How to connect the column at a detector side

Column end has to be located on the 2mm below of jet orifice

(Insert the column to the end of detector inside and then pull out around 2mm)

Installation method for nut and ferrule is same

with injection port.

In case of ECD, measure 72mm from the

ferrule and cut the column

Column Conditioning

Thermal conditioning

- Do not connect to the detector

- Set the carrier gas flow

- Conditioning as below

100℃

1 hr

2~3 /min℃

Max. temp. -30 ℃

Thermal conditioning

Column conditioning is essential like idling for car!

Solvent rinsing can remove soluble contaminants inside of bonded capillary column

Cleaning using solvent

Solvent volume and pressurefor cleaning

Column I.D.SolventVolume

ReservoirPressure

0.18mm 10ml 50 psi

0.25mm 15ml 40 psi

0.32mm 25ml 30 psi

0.53mm 50ml 15 psi

* Do not rinse the non-bonded column

Detector

Detectors Types

- TCD : Thermal Conductivity Detector

- FID : Flame Ionization Detector

- ECD : Electron Capture Detector

- NPD : Nitrogen Phosphorous Detector

- FPD : Flame Photometric Detector

- PDD : Pulsed Discharge Detector

- MSD : Mass Selective Detector

Selection Guide

Non active gasFormaldehyde

START

Simple chemicalHigh concentration

CompoundContaining

halogen

Compound Containing

Nitrogen/phosphorus

CompoundContaining

Phosphorus

CompoundContaining

Sulfur

TCD

ECD

NPD

YY

YY

N

NN

N

N

Y

FID

N

Y

FPD

PDHID

PDHID

PDECD

Characteristics of detectors

Detector type Analytes MDL Linearity

FID S have to ionized 5pg C/sec 10 (*7) on the H2/Air flame

TCD G All compounds 400 pg/ml carrier 10 (*6) (low sensitivity)

ECD S Halogen containing 0.1pg Cl/sec 10 (*4) compounds

NPD S N, P containing 0.4 pg N/sec 10 (*3) compounds 0.2 pg P/sec

FPD S P, S containing 20 pg S/sec 10 (*3) compounds 0.9 pg P/sec 10 (*

4)

MSD G All compounds 10 pg –10ng 10 (*5)

S: Selectable G : General

Sensitivities

TCD

ECD

FID

NPD

PDHID

FPD

PDECD

10-15

1ppt

10-12

1ppb

10-9

1ppm

10-6

0.1%

10-3 g

100%

TCD

Non destructive General detector

Measure the differences between sample and carrier

4 Filaments

Linearity : 106

Gas purity, Natural gas

FID

Measure the current of ionized sample by the H2/Air flame

Linearity : 107

Organic solvent, organic compounds, food, flavor, etc.

ECD

Respond to the compounds

have high electro negativity

Halogen, Nitro group, Organometalic, Oxygenated compound

Linearity : 104

Pesticides, PCBs, VOCs

NPD

Similar structure to FID. Bead(Alkali salt) increase the ionization of the compounds which contains N and P

Ionization of compounds which do not contain N and P is not allowed.

Linearity : 104

Pesticides, Pharmaceutical

FPD

Principle- Compounds containing S

and P : material that produces chemical emission is generated

- Produce the light of specific wavelength

- Amplify the light of specific wavelength (S:393nm, P:525nm)

PDD PDHID/PDECD Mode HID mode - Electron is produced by He discharge - Produced electron collides with He in the discharged area, and produce He** - He** collides with sample to ionize the sample

ECD mode - Xe(Dopant gas) is ionized to produce free electron - Standing current is formed by produced electron - When the sample is introduced, standing

current is decreased