Abstract
A solid sorbent tube (Patent No 4,292,042) employing an inhibited carbon preceded by a drying agent enables the hygienist to collect environmental air samples up to 90 liters at flow rates up to 1 liter per minute. Samples collected can be stored up to 10 days without loss of the vinyl acetate monomer. Analytical sensitivity of the method via gas chromatograph/flame ionization detection is 20 micrograms per milliliter which is equivalent to 1.33 milligrams per cubic meter or 0.4 parts per million by volume based on a 15 liter sample volume. Validation of the tube at the TLV, one-half the TLV and twice the TLV (recommended) shows greater than 98% recovery of known amounts of vinyl acetate generated through a dynamic dilution system at both low and high relative humidities. Breakthrough does not begin to occur until after sixty liters even at high relative humidity. No vinyl acetate is retained on the calcium sulfate. The use of calcium sulfate, a drying agent, as a precursor to the solid sorbent eliminates the effect of moisture on the monomer. Inhibiting the carbon prevents polymerization of the monomer after collection and during storage. The use of carbon as the adsorbent permits use of a liquid desorption medium. This technology is currently in use at several Union Carbide plants.