Determination of malachite green in fish water samples by cloud‐point extraction coupled to cation‐selective exhaustive injection and sweeping‐MEKC |
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Authors: | Xubiao Luo Xin Jiang Xinman Tu Shenglian Luo Liushui Yan Bo Chen |
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Institution: | 1. College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang, P. R. China;2. Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Hunan Normal University, Changsha, P. R. China |
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Abstract: | We have employed a high‐sensitivity off‐line coupled with on‐line preconcentration method, cloud‐point extraction (CPE)/cation‐selective exhaustive injection (CSEI) and sweeping‐MEKC, for the analysis of malachite green. The variables that affect CPE were investigated. The optimal conditions were 250 g/L of Triton X‐100, 10% of Na2SO4 (w/v), heat‐assisted at 60°C for 20 min. We monitored the effects of several of the CSEI‐sweeping‐MEKC parameters – including the type of BGE, the concentrations of SDS, the injection length of the high‐conductivity buffer, and the injection time of the sample – to optimize the separation process. The optimal BGE was 50 mM citric acid (pH 2.2) containing 100 mM SDS. In addition, electrokinetic injection of the sample at 15 kV for 800 s provided both high separation efficiency and enhanced sweeping sensitivity. The sensitivity enhancement for malachite green was 1.9×104 relative to CZE; the coefficients of determination exceeded 0.9928. The LOD, based on an S/N of 3:1, of CSEI‐sweeping‐MEKC was 0.87 ng/mL; in contrast, when using off‐line CPE/CSEI‐sweeping‐MEKC the sensitivity increased to 69.6 pg/mL. This proposed method was successfully applied to determine trace amounts of malachite green in fish water samples. |
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Keywords: | Cation‐selective exhaustive injection Cloud‐point extraction Malachite green Sweeping‐MEKC |
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