1.1 ,This test method is for the measurement of mercaptans (organic thiols) in the atmosphere at concentrations below 100 parts per billion (ppb(v) = 195 μ,g/m³). For concentrations above 100 ppb(v), the sampling period can be reduced or the trapping liquid volume increased either before or after aspirating. (See Practice D1357 for sampling guidance.) The minimum detectable amount of methyl mercaptan is 0.04 μ,g/mL (1)2 in a final liquid volume of 25 mL. When sampling air at the maximum recommended rate of 2 L/min for 2 h, the minimum detectable mercaptan concentration is 1.0 ppb(v) (1.95 μ,g methyl mercaptan/m³ at 101.3 kPa (760 mm Hg) and 25°,C). This test method determines total mercaptans and does not differentiate among individual mercaptans, although it is most sensitive to the lower molecular weight alkanethiols.