Application of ICP-MS as a multi-element detector for sulfur and metal hydride impurities in hydrocarbon matrices

Maturation of inductively coupled plasma-mass spectrometry (ICP-MS) in terms of size, reliability, and cost has had a significant impact on its consideration as a viable detector for gas chromatography. Its generally excellent sensitivity for those elements it can measure has been a contributing factor. A method for sulfur speciation in various hydrocarbon products is investigated, as well as sulfur and metal hydride contaminants in high purity hydrocarbon feed stocks. Detection limits for sulfur species in hydrocarbon liquids and gases are approximately 5 and 10 ppb, respectively, as sulfur. Lower detection limits on the order of 100 parts per trillion are achieved for arsine. The use of collision cell technology (CCT) is exploited to remove interferences. CCT has been described elsewhere (1) using helium or helium-hydrogen mixtures for suppression of 16O16O + interference with 32S. In this work, a novel approach is investigated which uses oxygen to remove this interference by shifting it in a comprehensive fashion. The advantage of operating the system at full power with a tandem gas and liquid interface is also discussed.