Analytical Sciences

Determination of Chromium(III) and Total Chromium in Water by Derivative Atomic Absorption Spectrometry Using Flow Injection On-line Preconcentration with a Double Microcolumn

Han-wen SUN,  Wei-jun KANG, Shu-xuan LIANG, Jing HA, and Shi-gang SHEN

College of Chemistry and Environmental Science, Hebei University, Baoding, 071002, China

A rapid and sensitive method has been proposed for the sequential determination of chromium(III) and total chromium in water samples by flame atomic absorption spectrometry combined with a flow injection on-line preconcentration on a double-microcolumn. The chromium(III) and total chromium in samples were retained on a double-microcolumn with a cation exchange resin, respectively, and eluted directly into a nebulizer by 3 mol L^-1 HNO₃. The characteristic concentration (gives a derivative absorbance of 0.0044) and the detection limit (3sigma) for chromium were 0.512 µg L^-1 and 0.647 µg L^-1 for a preconcentration time of 1 min, respectively. This is an improvement of 20 and 14-times than those of conventional FI-FAAS. The proposed method allows the determination of chromium in the range of 0 - 90 µg L^-1 with a relative standard deviation of 3.63% at the 10 µg L^-1 level. The method has been applied for the analysis of chromium in reference water of National Research Center for Certified Reference Materials (GBW08607) and other water samples with satisfactory results.

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