Monitoring of dissolved reactive phosphorus in wastewaters by flow injection analysis. Part 1. Method development and validation

The optimisation and validation of a flow-injection (FI) procedure for dissolved reactive phosphorus (DRP) in wastewaters is described. The procedure is based on the formation of molybdophosphoric acid and subsequent reduction to molybdenum blue with tin(II) chloride. The limit of detection was 0.05 mg P l−1 and the linear range was 0–25 mg P l−1. Particular emphasis is placed on the suitability of the procedure for application in an automated on-line FI analyser. This includes a comprehensive examination of potential interferences in the analytical procedure and comparison of the performance of the method with two other established procedures. Temperature effects and long-term reagent stability were also examined. The results from the proposed FI procedure for DRP in 11 wastewater samples showed very good correlation with those from the standard batch procedure.