Determination of hexavalent chromium in leather by ion-exchange chromatography

Abstract

The determination of traces of hexavalent chromium in leather and in leather consumer goods is carried out by ion-exchange chromatography. Samples are extracted at pH7.5-8 with a phosphate buffer, according to the method of the current ISO 17075 Standard. The extracts are filtered and analysed by HPLC using an ion-exchange stationary phase and a PDA detector, without any clean up process. An ammonium sulphate electrolyte at pH8 is used as mobile phase. The determination of the recovery yields rates from 84 to 108%. The HPLC method is compared with the current ISO 17075 Standard, which is based in the classical method of the diphenylcarbazide. The data from these results, and from those of recovery rate studies, leads us to conclude that the HPLC method is a better alternative for determining chromium (VI) in leather samples. The new method shortens the procedure of the current ISO 17075 Standard, diminishes workload, reduces the amount of laboratory wastes and its results are much more precise. HPLC is able to measure the chromium (VI) concentration of samples up to 3mg/kg, the detection limit of the current Standard