Mercaptans are odorous substances offensive at low concentrations and toxic at higher levels. They are emitted from geothermal sources, industrial processes, and food processing facilities.
1.1 This test method covers measurement of the concentration of mercaptans (organic thiols) in the atmosphere at concentrations below 100 parts per billion (ppb(v) = 195 956;g/m3). For concentrations above 100 ppb(v) level, the sampling period can be reduced or the liquid volume increased either before or after aspirating. The minimum detectable amount of methyl mercaptan is 0.04 956;g/mL (1) 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) (1.95 956;g methyl mercaptan/m3 at 101.3 kPa (760 mm Hg) and 25176;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.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 8.7, 8.8, and Section 9.
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