Chahal Varinder Kaur, Singh Raghubir, Malik Ashok Kumar, Matysik Frank-Michael, Puri Jugal Kishore
Chemistry Department, Panjab University, Chandigarh-160 014.
J Chromatogr Sci. 2012 Jan;50(1):26-32. doi: 10.1093/chromsci/bmr007.
A new method involving pre-concentration on modified silica fiber is described for the speciation of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] in aqueous media. This method is based on the different chelating behavior of Cr(III) and Cr(VI) with morpholine-4-carbodithioate (MDTC). Both complexes are extracted on silica fiber modified by sol-gel technology by using 3-aminopropyltriethoxysilane (APS) as a precursor. All extracted samples are directly injected into an high-performance liquid chromatography injector for the simultaneous determination of Cr(III) and Cr(VI). Cr(VI) forms two different complexes, and Cr(III) forms a single complex with MDTC. Therefore, the concentration of Cr(VI) is determined directly from the peak area obtained at 5.4 min; whereas, the assay of Cr(III) is based on subtracting the peak area of Cr(VI) from the total peak area obtained at 4.3 min. Under the optimized conditions, the limits of detection for Cr(III) and Cr(VI) are found to be 0.7 ng/mL and 0.2 ng/mL, respectively.
本文描述了一种新方法，该方法涉及在改性硅胶纤维上进行预富集，用于水介质中铬(III)[Cr(III)]和铬(VI)[Cr(VI)]的形态分析。该方法基于Cr(III)和Cr(VI)与吗啉-4-碳二硫代酸盐(MDTC)的螯合行为不同。两种配合物都通过溶胶-凝胶技术，以3-氨丙基三乙氧基硅烷(APS)为前驱体，在改性硅胶纤维上进行萃取。所有萃取后的样品直接注入高效液相色谱进样器，用于同时测定Cr(III)和Cr(VI)。Cr(VI)形成两种不同的配合物，而Cr(III)与MDTC形成单一配合物。因此，Cr(VI)的浓度直接由5.4分钟处获得的峰面积确定；而Cr(III)的测定是基于从4.3分钟处获得的总峰面积中减去Cr(VI)的峰面积。在优化条件下，Cr(III)和Cr(VI)的检测限分别为0.7 ng/mL和0.2 ng/mL。
