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

Abstract

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 (3σ) 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.