Rapid screening and quantification of heavy metals in traditional Chinese herbal medicines using monochromatic excitation energy dispersive X-ray fluorescence spectrometry.

Traditional Chinese herbal medicines are subject to heavy metal contamination. Standard detection methods are too complicated, time-consuming, and expensive for routine analysis, so low-cost methods are in high demand for rapid on-site screening. This study reports a high-sensitivity X-ray fluorescence (HS-XRF) method to determine As, Pb, and Cd residues simultaneously in herbal medicines. It couples monochromatic excitation energy dispersive X-ray fluorescence spectrometry and the fast fundamental parameters method. Each test takes only 10-30 min and costs 1/10th to 1/5th of the standard method. The detection limits, precision and accuracy were evaluated using different approaches, and application notes in practice are also proposed. This study is the first attempt to establish and evaluate HS-XRF in analyzing multiple heavy metals in herbal medicines. This rapid screening method would promote the testing efficiency and thus improve the monitoring of heavy metal contamination in herbal medicines.

[Survey and assessment of heavy metals in soils and herbal medicines from Chinese herbal medicine cultivated regions].

Concentrations of As, Hg, Pb, Cd in soils and herbal medicine samples from cultivated regions of Anguo City in Hebei Province were analyzed and assessed, and the bioconcentration factors of different herbal medicines were studied and discussed as well. The results showed that the average contents of As, Hg, Pb, Cd in soils from herbal medicine cultivated regions were 12.9, 0.036, 15.6, 0.118 mg x kg(-1), respectively. Concentrations of heavy metals in soils were lower than class II of the soil environmental quality standard. When local soil background values of heavy metals were used as assessment standard, among the 16 cultivated regions the percentage of As, Hg, Ph, Cd belonging to lightly pollution class were 18.75%, 43.75%, 0%, 100%, respectively based on the single pollution index. And the Nemerow index results were between 1 and 2, which suggested the soils were at slight pollution level. However, when quality standard class II was used, both the single pollution index and Nemerow index did not exceed 0.7, which means that soils investigated were generally safe for cultivation of Chinese herbal medicines. The assessment of heavy metals in herbal medicines showed that the pollution indices of most herbal samples (< 95%) were lower then 1. Cd bioconcentration factors of Aster tataricus L. and Anemarrhena asphodeloides Bunge, Hg bioconcentration factors of Angelica dahurica (Fisch. ex Hoffm.) Benth. et Hook. f. and Glehnia littoralis F. Schmidt ex Miq. were above 1. Therefore, the accumulation characteristic of heavy metals in Chinese herbal medicines should be fully concerned when GAP base soil quality assessment was taken.