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Human health

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Products shown here are related to the application of thermal desorption to human health. Or find out more about human health applications.

Active sampling

Active sampling (pumped sampling) onto sorbent tubes is one of the most versatile TD sampling methods, used to target both known and unknown sample environments. This approach involves use of a pump to actively draw an air sample through the sorbent tube to trap the target analytes.

Breath sampling

Breath sampling is a valuable approach for obtaining information used for disease diagnosis, monitoring of metabolic stress and personal exposure to chemicals. Breath samples can be collected using a number of techniques, which can then be used with thermal desorption to extract and concentrate the VOCs, maximising sensitivity for analysis of trace-level target compounds while minimising interferences.

Direct desorption/thermal extraction

Direct desorption is a variation on the principle of dynamic headspace that can be used to rapidly screen small quantities of solid or semi-solid materials. Small samples are placed directly into empty TD tubes or via tube liners. These are then heated in a stream of inert gas to sweep volatiles directly from the sample matrix onto the focusing trap of the thermal desorption instrument, for subsequent analysis by GC.

Microchamber sampling

Microchambers are compact, stand-alone test chamber units that allow rapid sampling of vapour-phase organic compounds from a product or material, complementing small-scale chamber testing by third-party laboratories. Microchamber sampling is a type of dynamic headspace sampling and a powerful tool for increasing laboratory productivity. The technique is usually used in combination with sorbent tubes and off-line thermal desorption–GC–MS.

Sample extraction supplies

A range of supplies are required for the busy lab technician needing to perform sample extraction, whether automated or manual. A reliable supply of quality assured items such as vials, caps, liners, syringes, fibers, and probes supports throughput.

Sorptive extraction

Sorptive extraction is an equilibrium process involving interaction between a sorbent and a sample, either by immersion in the sample or through contact in the headspace above the sample. It is commonly used as an alternative to liquid–liquid extraction (LLE) or solid-phase extraction (SPE). Sorptive extraction is a convenient approach for complex samples and for monitoring persistent organic pollutants in foods, beverages and other products derived from natural sources.

SPME

Solid-phase microextraction (SPME) uses a small fiber coated with absorptive phase(s), to extract volatiles in either headspace or immersive modes. SPME extraction is an equilibrium process dependent on the partitioning of analytes between the sample matrix (either liquid, solid or headspace) and the absorptive phase. Analytes that become absorbed into the SPME phase are subsequently desorbed using a heated injector, before transfer to the GC column.

Supplies for standard methods

Markes’ application specialists are active on committees working on standard methods, and also in the development of products to support method compliance. A variety of standard methods are available for monitoring specific VOCs often in prescribed sample types. For example, an automobile industry standard method might focus on materials such as plastic, leather or foam.

Standards & calibration

Calibration of the complete analytical process is of paramount importance when conducting quantitative studies. For TD analysis, additional considerations should be made regarding the loading of standards to be representative of samples, with a variety of tools available to support this.

Headspace sampling

Headspace (HS) has been widely used for quantitative evaluation of VOCs in solid and liquid samples for many years. Samples are placed into vials, sealed and incubated. Once equilibrium is reached VOCs partition into the headspace at levels that are proportional to their concentration in the original liquid or solid sample. A precise aliquot of headspace vapour is then transferred/injected directly into the GC (traditional methods) or via an electrically-cooled

focusing trap for enhanced performance.

Starter kits

Markes’ starter kits are designed to provide the essentials needed to get a thermal desorption system up and running quickly, by providing a single package with items such as tubes, traps, tools and other accessories.