5.1 Small quantities of sodium, 1 to 10 μg/L, can be significant in high pressure boiler systems and in nuclear power systems. Steam condensate from such systems must have less than 10 μg/L. In addition, condensate polishing system effluents should have less than 1 μg/L. Graphite furnace atomic absorption spectroscopy (GFAAS) represents technique for determining low concentrations of sodium.

1.1 This test method covers the determination of trace sodium in high purity water. The method range of concentration is 1 to 40 μg/L sodium. The analyst may extend the range once its applicability has been ascertained.

Note 1: It is necessary to perform replicate analysis and take an average to accurately determine values at the lower end of the stated range.

1.2 This test method is a graphite furnace atomic absorption spectrophotometric method for the determination of trace sodium impurities in ultra high purity water.

1.3 This test method has been used successfully with a high purity water matrix.2 It is the responsibility of the analyst to determine the suitability of the test method for other matrices.

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