Simultaneous determination of trivalent chromium and hexavalent chromium in plastics by accelerated solvent extraction-ion chromatography

A method based on accelerated solvent extraction-ion chromatography(ASE-IC) was developed for the simultaneous determination of trivalent chromium(Cr(Ⅲ)) and hexavalent chromium(Cr(Ⅵ)) in plastic samples.The accelerated solvent extraction was employed as the pretreatment method for the simultaneous extraction of the Cr(Ⅲ) and Cr(Ⅵ) from the samples.Cr(Ⅲ) and Cr(Ⅵ) were derivatized with 2,6-pyridinedicarboxylic acid(PDCA) and 1,5-diphenyl-carbazide(DPC),and detected by an ultraviolet-visible(UV-Vis) detector at UV and visible wavelengths,respectively.The results showed that the limits of detection for Cr(Ⅲ) and Cr(Ⅵ) were 5.0 μg/L and 0.5 μg/L and the good linearities of the calibration curves for them were in the ranges of 50-1 000 μg/L(r2=0.999 4) and 5.0-100 μg/L(r2=0.999 8),respectively.The recoveries were between 90.7% and 101.1% with the relative standard deviations(RSDs) of 1.7%-4.4% for Cr(Ⅲ) and Cr(Ⅵ).The method is sensitive,reproducible and adaptable to the simultaneous determination of Cr(Ⅲ) and Cr(Ⅵ) in the plastic samples.