Determination of Dibenzothiophene in SRM 1582, Wilmington Crude Oil and Addendum

摘要

The concentration of dibenzothiophene (DBTP) in SRM 1582 has been measured for eight samples using the standard technique in conjunction with a sulfur-specific dual-flame photometric detector (FPD) operating in the normal mode. The response of the FPD is not linear with the concentration of sulfur-containing compounds, but approximately with the square root of the response. The exact power of the response (linearization exponent) which is linear with concentration depends not only on the type of sulfur compound measured, but also to some extent on daily changes in the gas chromatographic instrument, such as slight changes in the flow of air, hydrogen or carrier gases, temperature changes, and detector geometry. In order to avoid these changes being possible sources of error and to determine the correct linearization exponent, detector calibration runs similar to the sample runs were performed on the day of analysis. Moreover, interfering peaks around the dibenzothiophene dictated that some sort of sample clean-up was necessary. To this end, the oil sample was first fractionated on a liquid chromatograph (LC), then concentrated prior to gas chromatographic analysis. (ERA citation 11:006954)