Determination of a 24-hour time-weighted average value of environmental vinyl chloride monomer concentration by charcoal adsorption followed by gas chromatography

Abstract

The method described was developed under the auspices of the Chemical Industries Association Vinyl Chloride Monomer Analysis and Monitoring Committee at the request of the Chief Alkali Inspector. A peristaltic pump draws the atmosphere through a tube packed with activated charcoal when vinyl chloride monomer is absorbed on the charcoal. At the end of the 24-h sampling period, the charcoal is extracted with carbon disulphide and the vinyl chloride in the extract determined by gas chromatography. The method has a limit of detection of 0.005 p.p.m. V/V and a precision under laboratory conditions of about ±10% relative. Interference by other known or expected atmospheric contaminants is negligible. Its accuracy in the field cannot be defined, but experiments using two different flow-rates simultaneously showed agreement to about ±10% relative.