Gas chromatography-mass spectrometry/selected ion monitoring for screening asymmetric epoxidation of styrene.

A screening method by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) has been developed for asymmetric epoxidation of styrene. All samples were analyzed by GC-MS with the mode of SIM by using ethylbenzene as the internal standard, by which styrene and styrene epoxide enantiomers were completely separated and their concentrations were accurately determined. Furthermore, this method was used to evaluate the epoxidation reaction of styrene, which was optimized by orthogonal experiment. The advantages of the method are as follows: excellent precision (RSD in the range of 1. 2% - 5. 2%, n= 5), good linearity (the correlation coefficients for styrene, (R)/(S)-styrene oxide were 0. 9997, 0. 9932 and 0. 9963, respectively) , low limits of quantitation (LOQs of styrene, (R)/(S)-styrene oxide were 1. 3, 1. 1 and 0. 7 mg/L, respectively) and reasonable recoveries (98. 2% - 108. 2%). All in all, the method provided a new way to determine the asymmetric epoxidation mixture of styrene and its homologs.