Fast room temperature cloud point extraction procedure for spectrophotometric determination of phosphate in water samples

A novel fast room temperature cloud point extraction (RT-CPE) procedure for preconcentration and spectrophotometric determination of phosphate based on the heteropoly blue formation was developed. The proposed method includes the formation of yellow molybdoantyrnonatophosphoric heteropoly complex, its extraction into Triton X-100 micellar phase obtained at room temperature and reduction of heteropoly complex by ascorbic acid solution in ethanol and absorbance measurement of heteropoly blue at 790 nm. Under optimal conditions (1% (v/v) of Triton X-100 and 0.05 M of ammonium benzoate for initiating of RT-CPE; 0.13 M ethanolic solution of ascorbic acid for reduction of heteropoly complex and dilution of surfactant rich phase), the calibration graph is linear in the range of phosphate concentrations of 1.58-63 mu g L-1. The proposed RT-CPE procedure has been successfully applied to preconcentration phosphates and its spectrophotometric determination in water samples.