DEVELOPMENT OF EFFICIENT CLOUD POINT EXTRACTION METHOD FOR PRECONCENRATION AND SPECTROPHOTOMETRIC DETERMINATION OF NICKEL IN WATER SAMPLES USING 2-(BENZOTHIAZOLYLZAO)ORCINOL

Objective: Efficient cloud point extraction (CPE) methodology was developed for pre concentration of trace nickel in water samples prior to their determination by spectrophotometry. Methods: The method is based on the reaction of nickel with 2-(benzothiazolyl azo) orcinol reagent (BTAO) at pH 7.0 and micelle-mediated extraction using the nonionic surfactant Triton X-114 medium. Results: The surfactant-rich phase was diluted with methanol and the nickel content was determined at 558 nm. The optimum conditions (e. g. pH, reagent and surfactant concentrations, and temperature and centrifugation times) were evaluated and optimized. The proposed CPE method showed linear calibration within the range 10–250 ng/ml of nickel and the limit of detection of the method was 2.0 ng/ml with a pre concentration factor of  50. The relative standard deviation (RSD) and relative error were found to be 1.10% ( N = 6). The interference effect of some cations and anions was also studied. Conclusion: The method was applied to the determination of nickel in water samples with a recovery from the spiked samples in the range of 95.85–98.50%.