4.1 Sodium is a pervasive contaminant and it is the first cation to break through deionization equipment. This test method allows measurement of micrograms per litre (parts per billion) concentrations of sodium in water to monitor low-sodium water sources for indications of contamination or proper operation. 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 inch-pound units given in parentheses are for information only.

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 and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements see Section 6.