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 (). It is generally applicable over the range of 0.01 to 10 000 g/L.1.3 The analyst should be aware that adequate collaborative data for precision and bias statements as required by Practice D 2777 are not provided. See Sectio