Determination of Trace Lead and Cadmium in Traditional Chinese Medicine by Flow Injection-on-Line Preconcentration-Inductively Coupled Plasma Optical Emission Spectrometry
Using a micro-column packed with polyethylenimine aminated glycidyl methacrylate-grafted-polytetrafluoroethylene fiber made by ourselves as the adsorption material,the adsorption behaviors of Pb and Cd under different conditions were studied by inductively coupled plasma optical emission spectrometry.The conditions for the preconcentration of Pb and Cd such as pH,flow-rate,time and eluent acidity were optimized.The results show that the PTFE-g-GMA-PEI Fiber has excellent adsorption property and high adsorption capacity for Pb2+ and Cd2+.The Enrichment factors for Pb2+ and Cd2+ were 30 and 80,respectively and the detection limits were 3.5 μg/L and 0.15 μg/L,respectively,the relative standard derivations were 1.5% and 0.6%(n=9)respectively.When the single ion concentration was 50 μg/L,the sampling frequency was 9 and 18 times/h,respectively.The method was applied to the simultaneous determination of trace lead and cadmium of several Chinese traditional medicine samples,the standard recovery of samples was 90%-108%.