Thermal desorption

Thermal desorption (TD) is a readily automated gas extraction technology based on standard gas chromatography and providing an efficient, high-sensitivity alternative to conventional solvent extraction. The process of thermal desorption involves the extraction of volatile or semi-volatile organic compounds from a sorbent or material by heating the sample in a flow of inert gas. Either pumped or diffusive monitoring are versatile sampling options for packed tubes, being compatible with both single- and multi-bed sorbents. Oxford Indices is ready to accept and analyse TD samples from any location. By providing clients with conditioned, sealed tubes and comprehensive instructions on sample preparation we can offer global coverage for testing any environment.

TD is specified by a number of international standard methods relating to indoor air. These include prENV 13419 and ISO DIS 16000 for testing emissions from building materials and US EPA Method TO-17, ISO 16017 Pt. 1 and ASTM D6196-97 for general monitoring of VOCs in indoor air. Industry standard ¼-inch outside diameter by 3.5-inch-long tubes can be sampled efficiently at rates ranging from 10 to 200ml/min, with the optimum being 50ml/min.

The UNITY–ULTRA-xr Multi-tube thermal desorber is an automated thermal desorption system for the rapid and unattended sampling of up to 100 sorbent tubes in a single sequence. The unit offers the following benefits:

• Security and reliability – Tubes remain capped at all times, thereby making automation mechanically simple and avoiding sample contamination and/or analyte loss.

• Simplified chain of custody – Tracking errors are eliminated by the on-board TubeTAG read/write functionality, which automatically updates tube and sample information during analysis.

• Wide concentration range – The availability of sample stacking increases sensitivity, while the ability to vary split ratios from splitless to 125,000:1 means that high-abundance and trace-level analytes can be monitored.