The determination of the non-volatile acidity of rain water by a coulometric procedure

Abstract

A precise and accurate method for the determination of the non-volatile acidity of rain water or of any dilute acid solution (10^–4 to 10^–6 M) is described. The method is based on the coluometric titration of a sample from which carbon dioxide has been removed by bubbling nitrogen through it. The end-point is detected by potentiometry with a glass electrode by using Gran's theory. The acidity from both strong and weak acids is determined. The average standard deviation is ±5 per cent. and the limit of sensitivity 0·1 µg ml^–1(calculated as sulphuric acid).