An automated procedure for the determination of phosphorus

Procedures for the determination of dissolved orthophosphate and total phosphorus in surface fresh waters (e.g. rivers. lakes and reservoirs) and organic wastes (e.g. domestic sewage. creamery effluents and the like) (particulate or dissolved) are described. Total phosphorus compounds are converted to orthophosphate by acid persulphate digestion. The digestion time is 3 h which goes to completion without any supervision. The method allows for a maximum of 36 samples. 2 blanks and 2 standards to be processed simultaneously. There is no pH adjustment required. Interference from silica and iron(III) up to 20 mg l⁻¹ is absent. Detection limits for the automated step involving orthophosphate are 1 μg 1⁻¹. Recovery and effectiveness of proposed procedures are excellent.