Trace-metal determinations in concentrated electrolyte solutions—a comparative study

Abstract

The results presented here are typical of those obtained during an extended study of methods for determining trace amounts of cationic contaminants in the two most commonly used dry-cell electrolytes (aqueous 7 M solutions of zinc chloride and potassium hydroxide). The results show that when dilution effects are taken into account there is little to choose between inductively coupled plasma atomic-emission and flame atomic-absorption spectroscopy as far as sensitivity is concerned but the precisions of results obtained from a direct reading (simultaneous) inductively coupled plasma spectrophotometer are significantly better than those obtained by flame atomic absorption, and the time taken to analyse samples for a number of elements is greatly reduced by the simultaneous inductively coupled plasma method.

At lower levels, significant reductions in sensitivity of the electrothermal atomic-absorption technique, amounting to 3–4 orders of magnitude in some instances, are caused by the presence of large excesses of these electrolytes, but where ultimate sensitivity is of less importance than sample throughput this technique has advantages over electroanalytical techniques. Where sensitivity, high precision and/or low capital costs are the prime consideration then electroanalytical techniques have much to offer.