Determination of Cr(Ⅲ) and Cr(Ⅵ) in Toys by Ion Chromatography

The sample was extracted through oscillation under dark with 0.07 mol·L^-1 of hydrochlorc acid solution (pH 1.0-1.5) at (37±2)℃, then Cr(Ⅲ) in the extract was derivatized with 2,6-pyridinedicarboxylic acid (PDCA) at 100℃ under pH 6.8. Cr(Ⅲ) derivative and Cr(Ⅵ) in the solution were separated on IonPac CS5A analytical column (250 mm×4 mm) and IonPac CG5A guard column (50 mm×4 mm), and Cr(Ⅵ) was derivatized with 1,5-diphenyl-carbazide (DPC) as a post-column derivative reagent. The derivatives of Cr(Ⅲ) and Cr(Ⅵ) were detected by an UV-Vis detector at 365, 530 nm respectively. The linearity ranges of Cr(Ⅲ) and Cr(Ⅵ) were 10-500, 0.1-5.0 μg·L^-1 respectively, with detection limits (3s) of 10, 0.1 μg·L^-1 respectively. Recoveries for Cr(Ⅲ) and Cr(Ⅵ) obtained by standard additon method were 80.0%-106%, and RSDs (n=7) were 0.52%-5.7%.