Monitoring of trace levels of p-dioxan in high purity benzene feedstock bycapillary gas chromatography

A procedure has been standardized for the determination of p-dioxan (1,4-di oxon) in benzene feedstock in the range of 1 to 100 ppm by capillary GC. Th e GC conditions such cis oven temperature, length of the column etc were op timized to achieve better resolution of p-dioxan from hydrocarbons. The sta ndard addition method of quantitation was used to determine the amount of p -dioxan and was found to give better results than those obtained by externa l standardization. Prior to analysis the identity of the p-dioxan peak was established by GC-MS. The proposed method has been applied for the monitori ng of p-dioxon in high purity benzene feedstock produced by the Udex extrac tion process in the refinery, The data were used for optimization of plant conditions for the production of high purity benzene feedstock. By using th is method, the p-dioxan content down to 0.5 ppm can be determined in the be nzene feedstock.