Sorbent Tubes

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Products shown here are concerned with sorbent sampling tubes for thermal desorption.

Empty sorbent tubes

Thermal desorption (TD) tubes are typically supplied packed with single or multiple sorbents, but there are a number of reasons why empty tubes might be chosen. These include direct desorption methods, self-packing or the need to pack with developmental sorbents for research purposes.

Sorbent tube end caps

Using appropriate end caps on your TD sorbent tubes is the best way of eliminating risks to sample integrity. As well as long-term brass storage caps, other types of cap include DiffLok™ caps, Diffusion caps and Aluminium push-on caps.

Pre-packed sorbent tubes

Pre-packed thermal desorption tubes are used to monitor VOCs, VVOCs and SVOCs. Compounds of interest are adsorbed onto the sorbents in the tube during active or passive sample collection, and subsequently desorbed by a thermal desorption system for analysis by GC–MS. Choose industry-standard tubes with our tube selector.

Sample tracking

Sample tracking is an important part of analytical quality control for users of thermal desorption, whether in high-throughput contract labs or in smaller studies also requiring traceability. There are several ways to track samples depending on budget and preferred technology. Markes recommends either the use of barcodes (a standard feature of Markes tubes) and scanner, or TubeTAG, a radio-frequency identification (RFID) tag that can be attached to a TD tube throughout its lifetime to log both sorbent/tube and sample information.

Sorbent tube conditioning

Conditioning refers to the process of heating sorbent tubes under a flow of clean carrier gas to minimise artefacts and remove contamination. In any sampling campaign employing thermal desorption tubes, it is vital that the sorbent bed is free from contaminants before sampling commences. This avoids complications during analysis and minimises the potential for false-positive results.

Sorbent tube customisation

Markes’ sorbent tubes are available in a variety of materials, sorbent packing combinations and with a wide range of labelling options. All Markes’ tubes feature sophisticated labelling with a unique ID number in clear barcode and numerical format, plus a sampling flow arrow. Tubes can also be customised to align with end-user and analyst workflow.

Sorbents

In the context of thermal desorption, a sorbent (or adsorbent) is a material used to capture volatile compounds. Sorbents are fundamental to the process of TD and are used in both sorbent tubes and focusing traps. Many types of sorbents are available, with some of the most popular being porous polymers such as Tenax^® TA, graphitised carbon blacks such as Carbograph and carbonised molecular sieves such as Carboxen 1000.

Tube & trap packing supplies

With the right experience and approach, self-packing of sorbent tubes can be a cost-effective option for thermal desorption. Sorbent choices, packing procedures and approach to tube conditioning are all factors underpinning the quality of data produced. It is crucial that users undertaking the packing of tubes themselves use the appropriate tools and supplies.