Liquid-membrane perchlorate-selective electrode

Abstract

A liquid-membrane electrode sensitive to the perchlorate anion has been prepared using berberine hydrochloride, an alkaloid that forms a nitrobenzene soluble ion pair with perchlorate. The electrode exhibits a Nernstian response over the range 1–10^–4M of perchlorate ion with a slope of 57 mV decade^–1 of activity. It also has a wide working range, i.e., from pH 1 to 13, under constant ionic strength (1.0 M NaCl). The response time is 15–50 s. Selectivity coefficients for various inorganic and organic anions were evaluated. The selectivity for the perchlorate ions relative to other common anions is reasonably high. A large number of anions, including hydroxy, thiocyanate and periodate anions, do not interfere. However, permanganate does interfere. The electrode was used to determine perchlorate in the presence of halides, sulphate, nitrate and chlorate.