Ion-selective electrodes in organic analysis: determination of amides via hydrolysis to carboxylates

Abstract

An indirect ion-selective electrode system for the determination of aromatic amides has been developed. In the presence of an excess of sodium peroxide, both primary and secondary amides were converted quantitatively into the corresponding carboxylates. Subsequently, the carboxylates obtained were determined, without further purification, using a tetraheptylammonium benzoate–poly(vinyl chloride) matrix membrane electrode. The electrode exhibited a Nernstian response in the concentration range 1 × 10^–1–7 × 10^–3 mol dm^–3 benzoate with an average slope of –47.2 mV per concentration decade. It has a working pH range of 7.0–9.5, a rapid response time (less than 3 min) and a stable response for at least 2 months.