The analysis of heavy metals in Chinese herbal medicine by flow injection–mercury hydride system and graphite furnace atomic absorption spectrometry

Abstract

INTRODUCTION: Simple and robust atomic absorption spectrometry (AAS) analytical methods were developed to determine the contents of arsenic (As), lead (Pb) and mercury (Hg) contained in Chinese herbal medicine products or Chinese proprietary medicine. OBJECTIVE: To develop AAS analytical methods to determine the contents of the toxic heavy metals in herbal medicine, and thus monitor them according to the regulated content limits to ensure the quality and safety of herbal products. METHODOLOGY: A flow injection-mercury hydride system technique was used for the quantitation of As and Hg, and a graphite furnace technique was used for the analysis of Pb. Limits of detection (LOD) for the three toxic heavy metals were found to be 0.3 ppb for As, 0.1 ppb for Pb and 0.5 ppb for Hg. Eight samples of 'Yin Qiao Jie Du' tablets available on the market were selected as the model herbal medicine for analysis. CONCLUSION: The developed analytical methods are sensitive enough to detect these heavy metals to meet regulated guidelines. No trace amounts of Hg were found in the test samples due to the fact that the Hg level is less than the LOD. However, variable amounts of As (135.0-5349.3 ppb) and Pb (22.5-968.3 ppb) were found in all products.