Determination of sulphate in natural waters and industrial effluents by sequential injection analysis

A sequential injection analysis system for the determination of sulphate in natural waters and industrial effluents has been developed. The method is based on the turbidimetric determination of sulphate using barium chloride as reagent and measuring the absorbance of the formed suspension spectrophotometrically at 540 nm. The proposed system is fully computerised and is able to monitor sulphate in samples at a frequency of 26 samples per hour with a relative standard deviation of better than 3.9%. The calibration graph is linear between 10 and 200 mg l−1.