Automatic determination of sulphate in water samples and soil extracts containing large amounts of humic compounds

Abstract

An automatic nephelometric method for the determination of sulphate in water samples, soil leachates and soil extracts is described. Dialysis of the samples eliminates interference from dissolved coloured humic compounds and suspended matter. The capacity of the method is 24 samples per hour and the precision is s= 0.49 mg l^–1 of sulphate-sulphur in the range 1–100 mg l^–1 of sulphate-sulphur. The method gives more reliable results for coloured samples than does the turbidimetric method with colour correction.