Technical innovation in trace organic analysis from Markes
For 20 years, Markes International has pioneered analytical thermal desorption (TD) instrumentation and associated sampling equipment. Here are our most important breakthroughs:
- Inert valving – A patented valve design makes all our TD systems compatible with the widest possible range of VOCs and SVOCs, from C2 to C44 as well as thermally labile species.
- Re-collection of split flows – Splitting the flow of analytes before and/or after desorption of the focusing trap allows collection of the unanalysed portion onto a second sorbent tube. This overcomes the ‘one-shot’ drawback of older TD systems, and means that the sample can be analysed under different TD–GC conditions, aiding method development or validation. See Application Note 024 for more information.
- Removal of water from on-line and canister air streams – Developed in conjunction with the University of York, UK, the Kori-xr module for UNITY–Air Server-xr and UNITY–CIA Advantage-xr systems uses an electrically-cooled trap to remove airborne humidity prior to analyte trapping. This enables polar species and monoterpenes to be reliably monitored in on-line and canister air streams, without the analyte loss that is a problem with other water-management techniques such as Nafion™ dryers.
- Electronic control of gas flows – The differing impedance of the TD flow path depending on the stage of operation demands tight control of gas flows, which is only possible using electronic controllers. Being able to do this stabilises GC retention times, which is especially important in complex analyses.
- Cryogen-free operation – Use of electrically-operated Peltier coolers eliminates costly liquid cryogen used in other systems to cool the focusing trap.
- Backflush desorption of the focusing trap – Collecting the sample onto the sorbent tube or focusing trap in the opposite direction to desorption ('backflush desorption') allows use of multiple sorbent beds, extending the range of compounds that can be collected and analysed from a single sample.
- Diffusion-locking technology for sorbent tubes – Our patented SafeLok tubes provide unrivalled protection for trace and toxic samples, while our DiffLok caps eliminate the capping and recapping of sorbent tubes in high-throughput studies.
- Tube tracking – Introduced in 2007, our patented TubeTAG system enables tube history and sample information to accompany a tube throughout its lifetime.