Speciation of bio-available chromium in soils by solid-phase extraction and graphite furnace atomic absorption spectrometry [An article from: Analytica Chimica Acta]

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Description:
Speciation of bio-available chromium in soils was performed using extraction with 0.05M EDTA followed by strong anionic solid-phase extraction. The step gradient elution technique with 0.1 and 0.5M NaCl as eluent in sequence was sufficient to separate Cr(III) and Cr(VI) with recoveries of 99.7 and 93.4%, respectively. During the determination of separated chromium species by graphite furnace atomic absorption spectrometry (GFAAS), 10% ammonium nitrate solution was co-injected with the sample to eliminate the interferences from the eluent matrix containing high concentrations of chloride. Linear calibration curves over the range of 0-15ngmL^-^1 were obtained with good correlation coefficients (R^2=0.9976 for Cr(III)EDTA^-, and 0.9897 for Cr(VI)). The sum of the chromium species determined after separation was in good agreement with total chromium from EDTA extraction of NIST soil standard SRM2709 (0.688@mgg^-^1 Cr(III), 0.127@mgg^-^1 Cr(VI), 0.742@mgg^-^1 total Cr) and a local soil sample (0.030@mgg^-^1 Cr(III), 0@mgg^-^1 Cr(VI), 0.053@mgg^-^1 total Cr).