科研之友
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摘要
In this article, an organic-reagent-free method was described for the determination of Cr(VI) and Fe(III) by double-system double-wavelength sequential injection technique with a single sample injection. In this approach, the determination of Cr(VI) was based on the detection of a blue unstable intermediate compound resulting from the reaction of Cr(VI) with hydrogen peroxide, and the determination of Fe(III) was based on the color reaction of Fe(III) with thiocyanate in acidic medium. Sequential injection analysis (SIA) parameters, including spacer solution volume, aspiration order, aspiration volumes, flow rate, acid medium, solution acidity, and reagent concentrations, were optimized. The linear range for the determination was 3.0-60.0gmL(-1) for Cr(VI) and 1.0-40.0gmL(-1) for Fe(III), respectively. The limit of detection (LOD) was 0.6gmL(-1) for Cr(VI) and 0.2gmL(-1) for Fe(III), and the limit of quantitation (LOQ) was 2.0gmL(-1) for Cr(VI) and 0.67gmL(-1) for Fe(III). The total volume of the reagent consumed in each determination was only 0.11mL. The proposed method was applied to the simultaneous determination of Cr(VI) and Fe(III) in electroplating wastewater and environmental waters. The results were in good agreement with those obtained by atomic absorption spectrometry. The recoveries were in the range of 97.5-101.1%.
