This International Standard specifies a method for the detection of hydrogen sulfide in liquefied petroleum gases. The lower limit of detectability is 4 mg of hydrogen sulfide in 1 m3 of liquefied petroleum gas. Methyl mercaptan, if present, produces a transitory yellow stain on lead acetate paper which, however, fades completely in less than 5 min. Other sulfur compounds present in liquefied petroleum gas do not interfere with the test. NOTE 1 Liquefied petroleum gases and the products of their combustion should not be unduly corrosive or reactive to materials with which they come into contact. It is therefore important that the presence of any hydrogen sulfide, a highly reactive substance, be detected. Additionally, the odour of hydrogen sulfide is unacceptable in some applications of liquefied petroleum gases (e.g. lighter fuel).