MICROEMULSION-BASED HYDROGEL FOR TOPICAL DELIVERY OF INDOMETHACIN

Objective: A new cloud point extraction (CPE) method was developed for pre concentration of trace cobalt (II) in water samples. Methods: The method is based on the complexation reaction of Co (II) with 2-(benzothiazolyl azo)-4-nitrophenol reagent (BTANP) at pH 7.0 and micelle-mediated extraction using the nonionic surfactant Triton X-114 of the complex. Results: The enriched analyte in the surfactant-rich phase was diluted with methanol and the cobalt content was determined by spectrophotometry at 549 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 10–300 ng/ml of Co(II) and the limit of detection of the method was 1.5 ng/ml with a pre concentration factor of 50. The relative standard deviation (RSD) was found to be 1.20% ( N = 6). The interference effect of some cations and anions was also studied. Conclusion: The proposed method has been successfully applied to the determination of Co(II) in water samples with a recovery from spiked samples in the range of 96.60–98.70%.