Determination of hexavalent chromium in traditional Chinese medicines by high‐performance liquid chromatography with inductively coupled plasma mass spectrometry

An analytical method that combined high‐performance liquid chromatography with inductively coupled plasma mass spectrometry has been developed for the determination of hexavalent chromium in traditional Chinese medicines. Hexavalent chromium was extracted using the alkaline solution. The parameters such as the concentration of alkaline and the extraction temperature have been optimized to minimize the interconversion between trivalent chromium and hexavalent chromium. The extracted hexavalent chromium was separated on a weak anion exchange column in isocratic mode, followed by inductively coupled plasma mass spectrometry determination. To obtain a better chromatographic resolution and sensitivity, 75 mM NH₄NO₃ at pH 7 was selected as the mobile phase. The linearity of the proposed method was investigated in the range of 0.2–5.0 μg L^?1 (r² = 0.9999) for hexavalent chromium. The limits of detection and quantitation are 0.1 and 0.3 μg L^?1, respectively. The developed method was successfully applied to the determination of hexavalent chromium in Chloriti lapis and Lumbricus with satisfactory recoveries of 95.8–112.8%.