Potentiometric system for the continuous determination of low levels of chloride in high-purity power station waters

Abstract

An analytical system for the continuous determination of low levels of chloride (0–150 µg 1^–1) in high-purity power station waters has been developed that is based on the potential of a silver-silver chloride electrode versus a mercury-mercury(I) sulphate reference electrode, the electrodes being immersed in a buffered sample stream. The temperature of the electrode flow cell is controlled at 10 (±0.1)°C, at which level the sensitivity of 3.54 mV per 100 µg 1^–1 is approximately 50% greater than that at 25 (±0.1)°C, and a linear response to changes in chloride concentration is observed over the range 0–150 µg 1^–1. The standard deviations at 10 °C for nominal chloride concentrations of 50, 100 and 150 µg 1^–1 are ±1.7, ±2.8 and ±2.8 µg 1^–1, respectively. Substances normally present in these waters do not interfere appreciably.