1.1 These test methods cover the continuous determination of trace amounts of sodium in water using an ion-selective electrode and flame photometry. Two test methods are included:

1.2 Test Method A is based on continuous application of the sodium ion electrode as reported in the technical literature (1-3). It is generally applicable over the range of 0.05 to 10 000 µg/L.

1.3 Test Method B is based on the use of flame photometry. It is most applicable to measurements below 20 µg/L. Compared with Test Method A, it is less vulnerable to interference from other monovalent cations at low concentrations and can reach equilibrium with very low sample throughput.

1.4 The analyst should be aware that adequate collaborative data for precision and bias statements as required by Practice D2777 are not provided. See Sections 16 and 26 for details.

1.5 The values stated in SI units are to be regarded as standard. The inch-pound units given in parentheses are for information only.

1.6 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 hazard statements see Section 6.