| abstract |
Analysis of a series of samples is carried in an electrode cell (10) containing an ion-selective electrode (11). A base solution, to which a trace of the ion to be measured has previously been added, is run into the cell (10). To perform an analysis a small volume of solution, containing a known concentration of the ion is added, followed by an identical volume of sample. The pX or mV measurement before and after each of the two additions is recorded and the analytical result calculated. After analyzing the first sample, the cell is drained, without rinsing and the second sample analyzed in the same way. No blank determination is required. In more sophisticated versions of the technique, at least two additions of standard are made, one before and one after the sample. |