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Supplies, consumables and consultancy for sample preparation

Sampling technologies

With over 20 years of expertise in thermal desorption and sample preparation for GC, we have gained a reputation as a pioneer in the field, with a track-record of continued innovation in solving sampling challenges. Our knowledge and experience mean we know how to approach getting the best results when sampling VOCs from solids, liquids and gases.

Here, the Sampling Technologies team shares its answers to questions from customers. Also featured is a “Spotlight on…” section in which we highlight our range of products.

Your questions answered

Passive sampling by thermal desorption

The Sampling technologies team share highlights of where they helped one of our customers with their sampling challenges.


Is it possible to quantify target VOCs using passive sampling with the POcket Diffusive (POD) sampler? We need to report the concentration in the air as a ng/L value.


The POD sampler is quantitative and results can be calibrated in ng/L or µg/m3. First, calibrate your thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS) system with the compound or compounds being monitored. This is done by injecting liquid standard solutions into industry-standard-size sorbent tubes and analysing them using the TD system in the normal way. Then, when you run the sampled POD cartridges in empty TD tubes using the same conditions on the same system, you will be able to determine the mass of each compound of interest collected on each POD during sampling.

Once you’ve done this, all you need are the POD sampler uptake rates for each compound of interest and the relevant sampling/exposure times, and you’ll be able to determine the respective air concentrations for each compound on each sampler. Our list of published uptake rates covers the most common compounds. However, if you want to measure a compound that isn’t yet on the list, it’s relatively easy to determine uptake rates.


How does passive sampling with the POD sampler compare to pumped sampling and passive sampling using charcoal badge samplers?


Pumped sampling of compounds using sorbent tubes is a valid approach but you should consider whether the extra equipment and steps required fit with your needs. Also, pumps require calibration and the flow rates should be checked at the beginning and end of sampling.

Analysts have gradually moved away from charcoal badge samplers for a number of reasons. They are less reliable than passive samplers and require desorption using a solvent – often CS2 – which is a laborious process requiring significantly more laboratory time per sample. The solvent desorption process introduces multiple points at which errors can occur, has a significant environmental impact and there are health and safety concerns. Each sampling badge can only be used once, which is an extra cost per analysis.

If you have a sampling challenge you’d like to talk to the team about, get in touch at

Spotlight on...

PFAS sampling tubes for thermal desorption

Per- and polyfluoroalkyl substances (PFAS) are a large class of fluorinated organic chemicals of environmental concern.

Markes International has developed a new range of sorbent tubes and an optimised focusing trap for sampling and analysing PFAS in air by TD–GC–MS.

Tubes for pumped sampling of indoor or outdoor air are available in stainless steel or glass in packs of 10. They can either be capped and conditioned or uncapped and packed with an optimised sorbent selection.

Meet the team

For large or complex projects, the Sampling Technologies team offers a tailored consultancy service, which encompasses engineering, sampling techniques and method development. Please contact the team by phone, email or live chat to discuss your application or project collaboration ideas. The team is led by Damien Cull, Sampling Technologies Business Unit Manager at the Markes International headquarters in the UK. For training on our products and/or applications, the Schauenberg Analytics Academy offers a range of courses, delivered by our product and application specialists (see below).

Josh holds a BSc in Analytical chemistry from the University of South Wales. He has worked in a number of ISO:17025 accredited laboratories, holding the roles of analyst and technical analyst focusing on method development using GC–MS and LC–MS.

Josh joined Markes in 2021 as the technical product specialist for the Sampling Technologies business unit. His role involves the development and validation of sampling products before release to market. The technical product specialist role also sees Josh provide technical support to customers who require help with Markes sampling products.

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Nick Bukowski started his mass spectrometry ('MS') career with the VG manufacturing group of companies. He held numerous MS roles including applications lab manager leading up to the company’s transition to Thermo Finnigan.

Nick managed a number of Informatics research programmes before becoming the product manager for the Thermo TEMPUS TOF system.

After a spell with Anatune in the UK, Nick joined Markes International in 2009 where he now manages cross-group product development.


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Jon joined Markes International in 2021 as an applied research scientist for the Sampling Technologies business unit. Jon holds a BSc in chemistry, a PhD in analytical chemistry (mass spectrometry) and is a Chartered Chemist (CChem) and a Fellow of the Royal Society of Chemistry (FRSC). He has over two decades of experience in mass spectrometry and has gained significant expertise in sample preparation and extraction. Jon has published over 50 peer-reviewed articles and has been involved in the development of many patented technologies.


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Training courses

We also offer training with the Schauenburg Analytics Academy, which provides fully interactive online and classroom-based courses hosted by applications and engineering specialists from Markes and SepSolve.