Rapid determination of dissolved organic phosphorus in soil leachates and runoff waters by flow injection analysis with on-line photo-oxidation

Abstract

A rapid method suitable for the determination of dissolved organic phosphorus (DOP) in soil leachates and runoff waters is presented. The flow injection (FI) manifold contains an in-line PTFE reaction coil wrapped around a low power UV lamp and is based on the spectrophotometric determination of dissolved reactive phosphorus (DRP) and mineralised DOP at 690 nm after reduction of phosphomolybdate to molybdenum blue with tin(II) chloride. The linear range was 0-1.5 mg l-1 PO4-P, with a detection limit (3 s) of 7 μg l-1 and a sample throughput of 40 h-1. Tolerance to potential matrix interferences in soil pore waters, particularly AI(III), Si(IV), Fe(II) and Fe(III), was achieved using a combin..