[Determination of trace lead in Chinese medicinal materials by GFAAS with PdCl2 as a matrix modifier]

A method for the determination of lead in Chinese medicinal materials by GFAAS with PdCl2 as a matrix modifier was established. By comparing PdCl2 with NH4H2PO4 in improving effect on the determination of Pb, the dosage of PdCl2, acidity of medium, interference of coexistent ion, recovery of the method, precision of the method, and the detection limit were checked. The programmed temperature of graphite furnace was optimized. The results show that the improving effect of PdCl2 on Pb determination is better than that of NH4H2PO4. The dosage of PdCl2 is 0.3 microg. The best medium should be 1.0% HCl. The three kinds of acids, 0.4% H2SO4, 1.0% HClO4 and 1.8% HCl, did not weaken the signal of lead. The recovery of the method is 90%-104% and the precision is < 5.0%. The characteristic mass is 8.5 pg. The detection limit is 0.066 mg x kg(-1). It is concluded that the method is simple, sensitive, accurate and credible, and can be used widely.