1.1These test methods cover the bubbler collection and colorimetric determination of sulfur dioxide (SO₂) in the ambient or workplace atmosphere.

1.2These test methods are applicable for determining SO₂ over the range from approximately 25 μg/m³ (0.01 ppm(v)) to 1000 μg/m³ (0.4 ppm(v)), corresponding to a solution concentration of 0.03 μg SO₂/mL to 1.3 μg SO₂/mL. Beer's law is followed through the working analytical range from 0.02 μg SO₂/mL to 1.4 μg SO₂/mL.

1.3The lower limit of detection is 0.075 μg SO₂/mL (1),2 representing an air concentration of 25 μg SO₂/m³ (0.01 ppm(v)) in a 30–min sample, or 13 μg SO₂/m³ (0.005 ppm(v)) in a 24–h sample.

1.4These test methods incorporate sampling for periods between 30 min and 24 h.

1.5These test methods describe the determination of the collected (impinged) samples. A Method A and a Method B are described.

1.6Method A is preferred over Method B, as it gives the higher sensitivity, but it has a higher blank. Manual Method B is pH-dependent, but is more suitable with spectrometers having a spectral band width greater than 20 nm.

1.7The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.8Warning—Mercury has been designated by many regulatory agencies as a hazardous material that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for additional information. Users should be aware that selling mercury and/or mercury containing products into your state or country may be prohibited by law.

1.9This 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. For specific precautionary statements, see 8.3.1, Section 9, and A3.1.3.