FLUORESCENCE QUENCHING METHOD FOR DETERMINATION OF TRACE TUNGSTEN IN SOIL AFTER CLOUD POINT EXTRACTION

A new procedure for trace tungsten W(VI) in soil by fluorescence quenching method coupled with cloud point extraction (CPE) as the separation-preconcentration method was described. The Triton X-100 CPE behavior of W(VI)-salicylfluorone (SAF) was investigated. Under the optimized conditions, the fluorescence quenched intensity (Delta F) was linearly with W(VI). The range of linear was 0.8 similar to 20.0 mu g . L-1, the detection limit (DL) was 0.14 ng . mL(-1) (3 sigma), the relative standard deviation 3.3% (c = 10.0 mu g . L-1, n = 5) and the recovery was 101.0-102.2%. The proposed method applied to the analysis of W(VI) in certified reference materials and real samples.