Determination of Cr(III) and Cr(VI) by Ion Chromatography
a J.E. Purkyně University, Faculty of Environment, Ústí nad Labem, b Research Institute of Inorganic Chemistry, Ústí nad Labem
Simultaneous separation and determination of Cr(III) and Cr(VI) was carried out on a multifunctional ion-exchange column Dionex IonPac CS5A in the anion-exchange mode. Cr(III) cations were converted to negatively charged complexes by pre-column derivatization with cyclohexane-1,2-diamine-N,N,N',N'-tetraacetic acid (CDTA) prior to separation. The mobile phase contained 100 mmol l−1 ammonium acetate, 10 mmol l−1 sodium perchlorate and 2 mmol l−1 CDTA. Post-column derivatization with diphenylcarbazide was employed for photometric detection of Cr(VI). The proposed method allows to determine Cr(III) at a level of 10−1 mg l−1 and Cr(VI) at 10−3 mg l−1 with high precision. Relative standard deviations of repeatability ranged from 0.6 to 3.9 % in dependence on the analyte concentration. The procedure was used for analyses of various industrial (plating baths) as well as environmental samples.
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