4.1 Sodium is a pervasive contaminant and it is the first cation to break through deionization equipment. This test method allows measuring sodium in low-sodium waters at micrograms per litre (parts per billion) concentrations to identify contamination or to monitor equipment performance. Applications include monitoring makeup systems, condensers, condensate polishers, feedwater, boilerwater, and steam.

4.2 This test method is more sensitive and selective than conductivity measurements on high purity samples.

1.1 This test method covers the on-line determination of trace amounts of sodium in water using an ion-selective electrode.

1.2 This test method is based on on-line application of the sodium ion electrode as reported in the technical literature (1-3).2 It is generally applicable over the range of 0.01 to 10 000 μg/L.

1.3 The analyst should be aware that adequate collaborative data for precision and bias statements as required by Practice D2777 are not provided. See Section 16 for details.

1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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. For specific hazard statements see Section 6.

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.