RÉSUMÉ
A new analytical method has been developed for the simultaneous determination of CrⅢand CrⅥusing on-line sample pretreatment valve-switching ion chromatography. The organic matrix in leather was removed by using a reverse-phase column as the pretreatment column. Before injection, EDTA was added into sample solution to react with the CrⅢto form anion which could absorb visible light strongly. After injection, the ions separated by the pretreatment column were received in a collection loop. Then the ions were delivered into an analytical column and separated. CrⅥ then was derived with the derivatization reagent 1, 5-diphenylcarbazide ( DPC) , and detected together with CrⅢ-EDTA complex by a UV-Vis detector. Under the optimum conditions, the linear range of the method for CrⅢ and CrⅥ was 0. 3-10 mg/L (r=0. 9991) and 0. 05-2 mg/L ( r = 0. 9992 ), whereas detection limits ( S/N = 3 ) were 80. 78 μg/L and 6. 67 μg/L, respectively. The recoveries were in the range of 88. 7%-108. 5% with the relative standard deviations for retention time and peak area less than 3%. The method could be applied to determine CrⅢ and CrⅥ in leather and cloth effectively and quickly.