Microcoulometric determination of trace sulphur in light petroleum products

Abstract

An investigation has been carried out into the coulometric determination of trace amounts of sulphur in volatile liquid petroleum products. The instrument used was a Dohrmann microcoulometer incorporating a combustion furnace, initially designed for the determination of sulphur in gas-chromatographic effluents. The original quartz combustion tube was replaced by a larger diameter tube to increase the residence time of gases in the combustion zone. The inlet was modified to allow direct injection of samples into the combustion tube and the inlet temperature was increased to 400° to 500° C.

The technique was applied to petroleum products ranging from naphthas to gas oils to determine the total sulphur content in the concentration range 2 to 1000 p.p.m. Precision and accuracy data are supplied, and factors affecting peak shape as well as interferences caused by halogen and nitrogen compounds are discussed.