UOP 1021-19

This method is for determining trace methyl mercaptan, ethyl mercaptan, and isopropyl disulfide in high purity polymer grade ethylene and propylene gas or liquid using a gas chromatograph equipped with a mass spectrometer run in selected ion monitoring mode. The specific instrument is preconfigured and is capable of determining typical impurities in polymer grade ethylene or propylene, however this method only outlines the procedure for determining methyl mercaptan, ethyl mercaptan, and isopropyl disulfide. Methyl and ethyl mercaptan elute on the propylene tail but are readily extracted by unique ions. The lower limit of quantitation for methyl and ethyl mercaptan are 0.04 mol-(or mass-) ppm and 0.02 mol- (or mass-) ppm for isopropyl disulfide.