The TT24-7 continuous air / gasmonitoring system incorporatestwo
electrically-cooled trapswhich operate in tandem toensure 100% data
capture
Continuous monitoring
The acute toxicity of many organicvapours means that near
real-time(NRT) data is sometimes required tominimise risk to human
health.Chemical processing plants andgovernment / military
installations arekey examples of sites which mayrequire one or more
NRT systems forround-the-clock operation.
Continuous monitoring may also berequired for general kinetic
studies -i.e. monitoring changes in vapour /odour composition over
time.Applications in this case range fromatmospheric chemistry and
biologicalresearch (e.g. monitoring the vapourprofile of growing
plants, moulds orinsect colonies) to food, flavour andfragrance
profiling.
Both of these application areasdemand continuous monitoring
andminimal cycle times. Typicalrequirements may include:
Data every 10 minutes or less
High sampling rate (>500 ml/min)for optimum sensitivity
100% data capture - i.e. trulycontinuous sampling
Reliability
On-plant installations for monitoringtoxic chemicals may also
requireunattended operation with remoteaccess to analyser set
points anddata. Transportability can also be akey factor - such
that systems can besafely deployed in the event of achemical
incident.
Introducing the TT24-7
Markes have developed an innovativecontinuous monitoring system
to meetthese needs. The model TT24-7 is arobust, transportable unit
convenientfor installation on-site or in mobileresponse vehicles as
well asconventional laboratories. It interfacesto GC(-MS) or
process MStechnology and incorporates twoelectrically-cooled traps
whichoperate in tandem to ensure 100%sampling efficiency (- no dead
times).
The Markes TT24-7 Near Real-Time Monitoring 24 hours per day, 7
days per week
Mi BTT24-7
Markes International Unit D3, Llantrisant Business Park,
Pontyclun, RCT, CF72 8RE, UK. Tel: +44 (0)1443 230935 Fax: +44
(0)1443 231531 http://www.markes.com [email protected]
The TT24-7 near real-time thermaldesorber
TT24-7 - transportable, near real-time thermal desorption
Installation in mobilelaboratories
TT24-7 Operation
Air / gas is first sampled onto thechannel A focusing trap
atelectronically controlled flow rates upto 1 L/min. At the end of
the samplingtime, channel B is switched in-linewhile channel A is
pre-purged,desorbed and analysed. Trap heatingrates approaching
100°C/sec combinedwith a reverse flow of carrier gasensure
efficient backflush desorptionof analytes over a wide boiling range
-giving narrow peak widths andoptimum sensitivity. When
samplingswitches back to channel A, channelB is desorbed and
analysed.
Patented inert valves inside the TT24-7isolate the sampling
process from theanalytical system allowing theanalysis to overlap
with collection of asubsequent sample. Sampling canproceed on the
desorption systemwhile GC or MS analysis of theprevious sample
continues.
System flexibility
The TT24-7 can operate standalone(i.e. connected directly to
theanalyser) or in combination with aUNITY desorber. Standalone
versionswork well for semi-volatiles which arerefocused on-column.
TT24-7-UNITYsystems offer the ultimateconcentration efficiency
(analyticalsensitivity) for volatiles - especially ifisothermal
chromatographic analysisis required.
Continuous monitoring with multi-stream selection.
Trace heated and ambienttemperature options are available
formulti-stream selection. Systems canbe custom configured to suit
yournetwork monitoring requirements.
Tube desorption for calibration andverification
The TT24-7 Tube DesorptionAccessory allows standards to
beintroduced to either of the focusingtraps from a sorbent tube.
Thisfacilitates routine calibration andallows certified reference
standardtubes to be introduced for auditinganalytical quality
assurance.
Parallel sampling onto a sorbent tubeat the inlet of a TT24-7
on-linesampling line also allows comparisonof on- and off-line
monitoring data forsystem verification. The sampledsorbent tubes
are analysed on theTT24-7 system via the TubeDesorption Accessory.
Since thequantitative recovery of GC-compatible organics from
sorbenttubes is well documented, satisfactorycorrelation of the
tube results withthose for the same sample analysedon-line verifies
analyte recoverythrough the on-line sample interface.
Two electrically-cooled, high efficiency sorbent traps operating
in tandem for100% sample capture
Markes International Unit D3, Llantrisant Business Park,
Pontyclun, RCT, CF72 8RE, UK. Tel: +44 (0)1443 230935 Fax: +44
(0)1443 231531 http://www.markes.com [email protected]
Mi BTT24-7
Three consecutive injections of Mustard Gas (HD) sampled onto
TT24-7
© Markes International 2004
2ng HD
2ng HD
1ng HD
TrapChannel B
TrapChannel A
Peltiercooling(fasterturnaround)
