Electrodes in series. Simultaneous flow injection determination of chloride and pH with ion-selective electrodes

Abstract

Chloride and pH can be determined simultaneously by flow injection potentiometry with a series electrode arrangement at a rate of 60 samples per hour, with a standard deviation of 1.5% for chloride and 1% for pH. Samples (30 µl) are injected into a carrier buffer solution (pH 7.6) containing 0.5 mol dm^–3 of potassium nitrate and 10^–2 mol dm^–3 of sodium dihydrogen phosphate as an ionic strength adjustment buffer. The sample-buffer zone formed is transported through a laboratory-made coated tubular solid-state chloride-selective electrode via a glass membrane micro pH combination electrode on to the reference electrode (for chloride). The method is suitable for the determination of chloride in the range 20–5000 mg dm^–3 and a pH range from 3 to 10.