[Determination of benzene and toluene in gasoline by two-dimensional gas chromatography and capillary column]

A novel two-dimensional gas chromatographic method, used for the determination of benzene and toluene in gasoline, was established by the capillary flow technology (Deans Switch) and universal capillary columns HP-5 (30 m x 0.32 mm x 0.25 microm) and Rtx-TCEP (30 m x 0.25 mm x 0.4 microm). Benzene, internal standard and toluene, which co-eluted with some saturated components from a non-polar column HP-5, were cut to a polar column Rtx-TCEP by Deans Switch and allowed to be fully resolved from saturated components. The linearity test showed that the correlation coefficient r2 values for benzene and toluene were 0.9994 and 0.9999, respectively. The results showed that the relative standard deviations (RSDs) of standard samples in five continued tests were within 1.5% and the recoveries of added standards tests were from 96.8% to 103.8%. This two-dimensional gas chromatographic method was compared to the standard analytical method for determining the concentrations of benzene and toluene in gasoline (SH/T 0713-2002). The results were in excellent agreement with the values obtained by SH/T 0713. The method is quick, simple and useful for the determination of benzene and toluene in gasoline.