Sulfur dioxide is a major air pollutant, commonly formed by the combustion of sulfur-bearing fuels. The Environmental Protection Agency (EPA) has set primary and secondary air quality standards (7) that are designed to protect the public health and welfare.

The Occupational Safety and Health Administration (OSHA) has promulgated exposure limits for sulfur dioxide in workplace atmospheres (8).

These methods have been found satisfactory for measuring sulfur dioxide in ambient and workplace atmospheres over the ranges pertinent in 5.1 and 5.2.

Method A has been designed to correspond to the EPA-Designated Reference Method (7) for the determination of sulfur dioxide.

1. Scope

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

1.2 These test methods are applicable for determining SO2 over the range from approximately 25 g/m³ (0.01 ppm(v)) to 1000 μg/m ³ (0.4 ppm(v)), corresponding to a solution concentration of 0.03 g SO2/mL to 1.3 g SO2/mL. Beer's law is followed through the working analytical range from 0.02 g SO2/mL to 1.4 g SO2/mL.

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

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

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

1.6 Method 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. Note 1These test methods are applicable at concentrations below 25 g/m ³ by sampling larger volumes of air if the absorption efficiency of the particular system is first determined, as described in Annex A4.

Concentrations higher than 1000 g/m ³ can be determined by using smaller gas volumes, larger collection volumes, or by suitable dilution of the collected sample with absorbing solution prior to analysis.

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. For specific precautionary statements, see 8.3.1, Section 9, and A3.11.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D1071 Test Methods for Volumetric Measurement of Gaseous Fuel Samples

D1193 Specification for Reagent Water

D1356 Terminology Relating to Sampling and Analysis of Atmospheres

D1357 Practice for Planning the Sampling of the Ambient Atmosphere

D1605 Practices for Sampling Atmospheres for Analysis of Gases and Vapors

D1914 Practice for Conversion Units and Factors Relating to Sampling and Analysis of Atmospheres

D3195 Practice for Rotameter Calibration

D3609 Practice for Calibration Techniques Using Permeation Tubes

D3631 Test Methods for Measuring Surface Atmospheric Pressure

E1 Specification for ASTM Liquid-in-Glass Thermometers

E275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers

Other Standards

Keywords

ambient atmospheres; analysis; colorimetric analysis; EPA reference method; pararosanaline method; sampling; sulfur dioxide; West-Gaeke procedure;

ICS Code

ICS Number Code 13.040.20 (Ambient atmospheres)

Citing ASTM Standards

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