The Determination of Trace Mercaptans and Sulfides in Natural Gas by a Gas Chromatography-Flame Photometric Detector Technique

Modifications to a gas chromatography-flame photometric detector (GLC-FPD) have been made to reduce losses to the system in the determination of C1-C4 mercaptans and sulfides in natural gas. These included moving the FPD and the gas sampling valve to minimize connecting tubing and modifying the FPD to reduce band spreading of sample components. Calibration was by a gas permeation tube system. Measurements made on t-butyl mercaptan blends at the 1 to 3 mole ppm level gave a standard deviation of 67 ppb. The technique will detect 0.1 mole ppm of t-butyl mercaptan and is specific for sulfur compounds.