Extraction efficiencies of heavy metals in hydroethanolic solvent from herbs of commerce

Heavy metal contamination of herbal products is a major concern in the herbal and dietary supplement industry. Heavy metal exposure is well-documented to cause a variety of adverse human health effects and to negatively impact our environment. The Final Rule for Dietary Supplements for current good manufacturing practice regulation, 21 U.S. Food and Drug Administration Code of Federal Regulations 111, requires dietary supplement manufacturers to establish herbal purity limits for heavy metal contaminants considered safe for human consumption. Heavy metals may enter into the herbal manufacturing process via bioaccumulation from the harvest site or during postharvest processing phases, such as drying and/or liquid extraction. Traditionally, herbalists have used hydroethanolic solvents to extract herbal biomasses in pure food-grade ethanol-water combinations with solvent polarities capable of removing a wide range of hydrophilic and lipophilic constituents. The presented data demonstrate that hydroethanolic solvents are not completely efficient in the extraction of heavy metal accumulations from plant matrixes; and can act as an effective decontamination step in herbal product processing.