Technology: Thermal desorbers

MARKES International

Fully automated multi-mode sampling and concentration system for GCMS.


Built using best-in-class robotic automation and harnessing a versatile, modular design, Centri allows unattended sampling and preconcentration of VOCs and SVOCs in liquid, solid and gaseous samples, and is compatible with all major brands of GC–MS.

Available options include:

  • HiSorb™ high-capacity sorptive extraction
  • HS & HS–trap
  • Thermal desorption
  • SPME & SPME–trap
    … all on ONE INSTRUMENT

HiSorb high-capacity sorptive extraction Convenient probes for immersive or HS sampling of liquids & solids.

HiSorb probes use high-capacity sorbent polymer to extract and concentrate a wide range of organic compounds from liquid and solid samples.
Reliable, high-throughput operation is delivered using a combination of innovative functions:

  • Simultaneous preparation/extraction of multiple samples (prep-ahead). Centri accommodates multiple HiSorb probes.
  • Efficient post-immersion removal of sample matrix residue before probe desorption.
  • Selective elimination of water and other volatile interferences before GC–MS analysis.
  • Optional quantitative re-collection of extracted vapours for sample security and/or further tests.

HS & HS–trap Versatile sampling from solids and liquids contained in regular headspace vials

Headspace techniques are widely used for analysing VOCs in water, soil, blood, pharmaceuticals and cosmetics. Although headspace overcomes the foaming issues associated with purge-and-trap methods, a drawback is that sensitivity is limited in conventional static (or equilibrium) headspace mode.
The cryogen-free focusing trap on Centri enables enhanced sensitivity for headspace, by allowing:

  • Larger (up to 5 mL) volumes of vapour to be injected onto the trap under splitless conditions.
  • Selective elimination of water and other volatile interferences that would otherwise quench or mask detector response.
  • Preconcentration of multiple headspace extracts from the same sample vial if required, to further extend analytical sensitivity.

Thermal desorption analysis of trace VOCs and SVOCs.

Method-compliant analysis of vapour-phase organics in air, gas and materials
Inert, metal or glass sorbent tubes are used to collect organic vapours from many litres of air or gas in accordance with standard methods. The organics retained by each sample tube are subsequently re-released and injected into the GC–MS allowing quantitation to ppt levels and below. Typical applications include characterising airborne odours and aromas, monitoring changing fragrance profiles, taint and off-odour diagnostics, and air/gas purity assessment.
The Centri TD module features world-leading, method-compliant thermal desorption technology compatible with reactive odorous species and compounds ranging in volatility from propene to n-C44.
Up to 50 sealed sample tubes can be analysed automatically and reliably, with optional sample re-collection.
Thermal desorption can also be combined with other injection modes in one fully automated Centri sequence. In addition, the Centri TD module can be used to analyse any re-collected and archived samples from previous HiSorb, HS–trap and SPME–trap analyses.

SPME & SPME–trap Fast and sensitive sample extraction, with a range of selective fiber types.

SPME is a convenient and readily-automated approach, typically used for sampling VOC and SVOC levels in the headspace of food, environmental and clinical samples. The availability of a variety of extraction phases for SPME fibers allows different volatility and polarity ranges to be targeted.
Combining SPME with secondary re-focusing on Centri enhances sensitivity by allowing multiple extraction cycles from a single sample to be ‘concentrated’ in one GC–MS run. It also significantly improves peak shape and signal-to-noise ratios for the most volatile, early-eluting

Application notes
Residual solvents in food packaging by automated headspace–trap GC–MS

Quantitation of residual solvents in food packaging by automated headspace–trap GC–MS

File size: 311 KB
Volatile organic pollutants in water by headspace–trap GC–MS

Quantitative determination of volatile organic pollutants in water using headspace–trap GC–MS

File size: 691 KB
Screening of butylated hydroxytoluene by automated headspace–trap GC–MS

Screening foods and beverages for butylated hydroxytoluene (BHT) using automated headspace–trap GC–MS

File size: 281 KB
Aroma with VOC profiles acquired by automated TD–GC–MS

Correlating consumer sensory experience of apple aroma with VOC profiles acquired by automated TD–GC–MS

File size: 333 KB


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