Two-point gran titration of chloride in natural waters by using a silver-sulphide ion-selective electrode

Abstract

A simple, rapid and precise determination of chloride in a stream or a lake water was performed without any sample pre-treatment by using the precipitation titration-Gran plot procedure. A good correlation was observed between the results obtained by potentiometry and by spectrophotometry or ion chromatography. The effects of various experimental factors on the accuracy and precision in Gran titration were examined. It was demonstrated that two titration points were sufficient to obtain a maximum precision of 0.2%, provided that the potential difference between them was chosen to exceed 20 mV. The two-point Gran titration method was applied to the analysis of streams and lake water with an error of less than 2% and compared with the usual multi-point Gran titration method.