GFAAS Simultaneous Determination of Ultra-trace Amount of Lead and Cadmium in Environmental Water and Chinese Traditional Medicine with Enrichment by Cloud Point Extraction

A new method for simultaneous determination of ultra-trace amounts of lead and cadmium in environmental water and Chinese traditional medicine by GFAAS was proposed in this paper.Ultra-trace of Pb2+ and Cd2+ was extracted from the sample solution in the form of coordination complex with dithizone at pH 7.0 by cloud point extraction with Triton X-114 as a non-ionic surfactant.A mixture of Mg(NO3)2 and NH4H2PO4 was used as matrix modifier.Values of detection limits for Pb and Cd were 0.138 and 0.007 μg·L-1 respectively.Values of RSD′s (n=7) of Pb2+ and Cd2+ were 1.90% and 2.08%,with enhancement factors of 18.3 (Pb) and 17.7 (Cd) in 10 mL sample solution.Standard reference materials of poplar leaf (GBW 07604) and wheat flour (GBW 08503) was analyzed by the proposed method,giving results of Pb and Cd found contents in consistency with the standard values.Values of recovery of Pb and Cd found by standard addition method were 97.8%,94.0% for enviromental water samples and 98.0%,94.0% for Chinese traditional medicine samples respectively.