Solid phase spectrophotometric determination of traces of arsenate and phosphate in water using polyurethane foam sorbent

A simple and sensitive method for the determination of arsenate and phosphate in the mugL-1 concentration range using solid phase spectrophotometry has been developed. The method utilizes the quantitative sorption of the heteropoly blue species of arsenomolybdic and phosphomolybdic acids by polyurethane foam (PUF) sorbent prior to direct spectrophotometric measurement of the solid phase. In the same time the difference in formation behavior between the arsenomolybdic and phosphomolybdic acids at different pH values of sample solution has allowed their determination in the presence of each other. A preconcentration factor of 150 has been achieved for 100 mL samples. The detection limits are 5.4 and 1.66 mug L-1 for arsenate/As and phosphate/P, respectively and the working analytical ranges are from 5.4-54 mug L-1 and 1.6-40 mug L-1 respectively. The different experimental parameters such as rate of color development, acidity of solution and the analyte concentration have been thoroughly investigated. Analysis of natural water samples has been performed.