Analysis of Thiophene in Benzene by GC-FPD

Introduction

Analysis of thiophene in benzene has long been conducted as part of the purity control for benzene. Recently, with the demand for higher purity benzene, there is increased demand for low concentration analysis for thiophene. Thiophene is a sulfur-containing five-membered heterocyclic compound, which is typically analyzed using an FPD operated in the sulfur mode (S-mode). Since the boiling point of thiophene is close to that of benzene, insufficient chromatographic separation of benzene and thiophene often occurs especially when analysis times are short, and then an FID is not available. Therefore, analysis is conducted using the selectivity of the FPD, carrying over the incomplete separation. However, high-sensitivity analysis of low concentration thiophene in benzene may not be possible, even using the FPD, because of the effect of quenching due to the principle constituent, benzene. The reduction of quenching by changing the FPD flow rates of hydrogen and air and the use of a thick-film capillary column to achieve high sensitivity analysis is the subject of this investigation.

April 19, 2007 GMT