Selective extraction of chromium(VI) using a leaching procedure with sodium carbonate from some plant leaves, soil and sediment samples

Abstract

Speciation of chromium in some plant leaves, soil and sediment samples was carried out by selective leaching of Cr(VI) using a sodium carbonate leaching procedure. Total chromium from the samples was extracted using aqua regia and oxidative acid digestion, respectively. The concentrations of chromium species in the extracts were determined using by graphite furnace atomic absorption spectrometry (GFAAS). Uncoated graphite furnace tubes were used as an atomizer. Due to the presence of relatively high amounts of Na 2CO 3 in the resulting samples, the possible influences of Na 2CO 3 on the absorbance signals were checked. There is no interference of Na 2CO 3 on the chromium absorbance up to 0.1 mol L −1 Na 2CO 3. A limit of detection (LOD) for determination of Cr(VI) in 0.1 Na 2CO 3 solution by GFAAS was found to be 0.93 μg L −1. The procedure was applied to environmental samples. The relative standard deviation, R.S.D. as precision for 10 replicate measurements of 20 μ L −1 Cr in processed soil sample was 4.2%.