processing herbal medicines in China for hundreds of years. According to the local
cultivated species, planting areas and locations, 12 typical herb medicine species were selected and samples were directly collected from field or purchased from markets or pharmacies (n = 197 in total). Based on a preliminary survey of total As in CHMs , a part of samples (n = 65) with high levels of total As in CHMs were selected to explore As speciation in this study.