SPECIATION OF DISSOLVED PHOSPHORUS IN ENVIRONMENTAL-SAMPLES BY GEL-FILTRATION AND FLOW-INJECTION ANALYSIS

A study of the factors affecting separation and detection of dissolved organic and inorganic phosphorus species found in waters and sediments is reported. The system involved the use of gel filtration and flow injection analysis (FIA). Orthophosphate and myo-inositol hexakisphosphate, as model solutes representative of low molecular weight P (LMWP) and high molecular weight P (HMWP), were separated on a Sephadex G25 column incorporated into a flow-injection manifold which utilized photo-oxidation and spectrophotometry for detection of dissolved reactive phosphorus (DRP) and dissolved organic phosphorus (DOP). The influence of eluent pH and ionic strength on adsorption and anionic exclusion of the model solutes is described, and the optimum eluent composition and sample size are described. The method was used to determine LMWP and HMWP in natural and waste waters, and in sediment extracts. Potential limitations of this approach are discussed.