Preconcentration and separation of trace phosphorus compounds in soil leachate

The speciation of P in soil solutions and runoff waters presents an analytical challenge that must be overcome before P transfer processes can be fully understood. We describe a method employing strong anion exchange (SAX) resins for the concentration and speciation of trace amounts of P compounds in soil waters. Concentration of P was achieved by passing filtered samples through SAX cartridges and eluting the retained negatively charged species with a solution of 0.75 M NaCl and 0.5 mM EDTA, Separation was achieved by the application of strong anion exchange HPLC with a linear ionic gradient varying between 0.11 to 0.75 M NaCl and a constant concentration of 0.5 mM Na(4)EDTA. Total P detection was carried out by discrete fraction collection and manual analysis using a sulphuric acid-persolphate digest followed by reaction with molybdate, We detected a range of P species in soil leachate water, which included orthophosphate, inositol hexaphosphate, glucose-6-phosphate, adenosine 5'-triphosphate, phosphonates and other as yet unidentified forms of P, With refinements, this method has the potential to significantly enhance our understanding of the P forms in soil waters and the processes controlling P transfer from the land.