Determination of elemental sulfur in gasoline by gas chromatography with on-column injection and flame ionization detection following derivatization with triphenylphosphine.
Several years ago, the presence of elemental sulfur in gasoline became a significant issue for the automotive and fuel industries. In several incidents, elemental sulfur at trace levels led to the corrosion of silver alloy fuel sensing elements in automobile gasoline tanks. This report describes a derivatization method that allows the determination of trace levels of elemental sulfur using flame ionization detection. The sample is derivatized with triphenylphosphine to form triphenylphosphine sulfide. This component is readily detected with a flame ionization detector. In most analyses, on-column injection was employed to allow detection of trace levels of elemental sulfur. However some analyses with splitless injection were also performed. For some gasolines, detection limits on the order of less than 1 microg/g elemental sulfur were possible with this approach. However, the detection limit can vary depending upon the concentration of trace higher boiling components. The precision of the analysis, as measured by the relative standard deviation of triplicate injections, for gasolines containing 1 to 10 microg/g of elemental sulfur was in the 1 to 3% range. The recovery of a gasoline spiked with approximately 4 microg/g elemental sulfur was 102%. The presence of ethanol did not appear to affect results.
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