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 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. It is the responsibility of the analyst to determine the suitability of the test method for other matrices. 1.4 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.