Proficiency testing schemes in Europe have shown that there was a need to improve the quality of the measurements to assess exposure to harmful chemicals in air at the workplace. Efforts were required to provide calibrants and CRMs for quality control.
Chlorinated hydrocarbons were important industrial chemicals at the time this project was selected (they are now being phased out) and are monitored in the atmosphere because of their role in the depletion of stratospheric ozone.

The project aimed at the preparation and certification a reference material consisting of stainless steel tubes (9 cm, PE type for thermal desorption) filled with graphitised Tenax-GR, charged with known levels of each of the four listed compounds, and capped with Swagelock caps using teflon ferrules.
Intercomparisons have been held and the results assessed to improve the analytical state of the art in the participating laboratories.
A reference material have been prepared (CRM 555), tested and analysed by a group of laboratories, has been certified, and is available from IRMM.
The work done under this contract consisted of:
the preparation and the homogeneity and stability testing of a reference material, related to the monitoring of chlorinated hydrocarbons (dichloromethane, 1,1,1-trichloroethane, trichloroethene and tetrachloroethene) in (workplace or ambient) air by trapping on a sorbent followed by thermal desorption and gas chromatography
to coordinate the collaborative analytical campaign for the certification of this material.