ASTM D4519-25

1.1 This on-line test method includes hydrogen exchange and degassing by heating or gas stripping and provides means for determining anions (such as Cl⁻, SO₄⁻, NO₃⁻, and F⁻) at levels as low as 2 μg/L (2 ppb) and carbon dioxide at the level of 0.01 mg/L to 10 mg/L (ppm) at 25 °C in high purity water and in steam and water samples in power plants by measuring electrical conductivity.

1.2 The conductivity of all anions (except OH⁻) is determined and not the conductivity of an individual anion if more than one is present. If only one anion is present (such as Cl⁻ or SO₄⁻), reference to Section 4, Table 1 and Table 2 or Figs. 1-3 provides the chloride or sulfate and CO₂ concentration.

1.3 This test method has been improved in accuracy by using a modern microprocessor instrument for conductivity and temperature measurement and appropriate temperature compensation algorithms for compensation, by using final sample cooling to 25 °C, or both.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.