This method is for determining methane, ethane plus ethylene, acetylene, methylacetylene, propadiene plus cyclopropane, 1,3-butadiene and 1,2-butadiene at the 1-500 mol-ppm level in liquefied petroleum gas (LPG). The lower limit of detection for any component is 1 mol-ppm. Other trace saturated hydrocarbons can be determined by UOP 899.