Determination of chromium(III) and chromium(VI) by use of a spectrophotometric sequential injection system Original Research Article

The importance of sequential injection analysis in speciation analysis is exemplified by the simultaneous determination of Cr(III) and Cr(VI) with an R.S.D. (n=10) of better than 0.7% for both Cr(III) and Cr(VI). The frequency of sampling is 30 determinations/h with a sample interaction of 1.1%. The linear range for Cr(III) is 0.85–25 mg l−1 and for Cr(VI) 0.16–20 mg l−1. The detection limit is 0.042 and 0.023 mg/l for Cr(III) and Cr(VI), respectively. Statistical evaluation showed that the proposed method performed very well in comparison to standard methods.