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.
Aromatic hydrocarbons are used worldwide as solvents and as fuel ingredients, but are of major concern in workplace air. Benzene is even of concern in typical ambient air.
For monitoring of aromatic hydrocarbons in air, the common techniques are based on trapping the compounds on a sorbent (either by diffusive exposure, or by pumping air through it) followed by desorption and GC analysis. The desorption is either done by heating ("thermal desorption") or by solvent extraction ("solvent desorption"). A reference material for the thermal desorption technique was previously certified (BCR CRM 112).
The project aimed at the preparation and certification a reference material for use with the solvent desorption technique. It would consist of a set of glass tubes containing activated charcoal, some tubes unopened, and some tubes charged with known amounts of benzene, toluene and m- and o-xylene.
A reference material have been certified (CRM 562) and is available from IRMM.
The work done under this contract consisted essentially of the actual certification of the material through an interlaboratory campaign. The preparation, homogeneity testing and stability testing of the material was covered by an earlier contract from the BCR programme.