[Determination of heavy metal in Chinese herbs]

Microwave digestion system was used in digesting samples. Lead and cadmium were determined by graphite furnace atomic absorption spectrometry. Mercury was determined by cold vapor atomic absorption spectrometry. Standard reference material (NBS1570), spinach powder was used as analysis quality assurance in this method, and 264 Chinese herbs (23 species) and standard reference material were determined, and satisfactory results were obtained by using this method. Averages recovery of lead, cadmium and mercury is 95.0%, 97.5% and 99.2% respectively. Limit of detection (LOD) is 0.006 mg/kg, 0.208 microgram/kg and 0.026 microgram/kg respectively for lead, cadmium and mercury. Limit of quantity (LOQ) is 0.019 mg/kg, 0.694 microgram/kg and 0.087 microgram/kg respectively for lead, cadmium and mercury. This method is also suitable to determine lead, cadmium and mercury in food.