Determination of airborne methyl tert-butyl ether in gasoline atmospheres

In the analytical method outlined in this paper airborne methyl tert-butyl ether (MTBE) and other hydrocarbon vapours are sampled by drawing the atmosphere through a primary sorption tube containing a porous polymer sorbent. A known volume of air is drawn by a suitable sampling pump, which may be worn by an operator or remain static at a specified location. Factors influencing the choice of sorbent are discussed. After sampling, the primary sorption tube is capped and returned to the laboratory for analysis. Sampled vapours are desorbed from the primary trap by thermal desorption. The desorbed sample is re-concentrated on a small secondary cold trap containing a solid sorbent. When desorption from the primary trap is complete, the secondary trap is heated rapidly and the sample (now in a very narrow plug) is swept on to a fused-silica capillary column that is located only a few millimetres from the sorbent bed of the secondary trap. MTBE is separated from gasoline hydrocarbons on an OV-1701 capillary column and quantified by a calibrated flame-ionisation detector.