Analysis of hexavalent chromium in Colla corii asini with on-line sample pretreatment valve-switching ion chromatography

An ion chromatography (IC) system with on-line sample pretreatment using valve-switching technique was developed for the determination of hexavalent chromium (Cr(VI)) in Colla corii asini . Colla corii asini is a complicated sample with organics as main matrix. In this work, a polymer-based reversed-phase column was used as a pretreatment column. Via valve-switching technique, sample solution with target ions were eluted from a collection loop to analytical columns, with matrix eliminated on-line. Under the optimized separation conditions, the method showed good linearity ( r   =   0.9998) in the range of 0.004–1.0   mg/L and satisfactory repeatability (RSD   <   3%, n   =   6). The limit of detection (LOD) was 1.4   μg/L (S/N   =   3). The average spiked recoveries of Cr(VI) were 93.4–102.0%. The result showed that the on-line sample pretreatment IC system was convenient and practical for the determination of trace Cr(VI) in Colla corii asini samples