Silver chloride pre-treatment for the direct potentiometric determination of chloride in stream waters using a solid-state chloride ion-selective electrode

Abstract

An effective pre-treatment for the direct potentiometric determination of chloride using a solid-state chloride ion-selective electrode is proposed, which is based on the addition of a freshly prepared suspension of silver chloride to a stream water sample. Bromide in the sample can be effectively removed by solubility exchange with chloride from the silver chloride suspension, thus removing the interference caused by silver bromide being formed on the electrode surface. Interference from iodide and sulphide can also be suppressed, although the degree of interference from these ions in low concentrations is much smaller than would be expected from the solubility products of their silver salts.

The 1–17% positive errors observed in the analysis of ten stream waters containing 6.67–40.0 mg l^–1 of chloride have been decreased to below 5% by the proposed pre-treatment.