GFAAS Determination of Lead and Cadmium in Soil

Sample of soil was digested with a mixture of HNO3, HF and H2O2, and the contents of lead and cadmium in sample solution was determined by GFAAS. Ammonium phosphate was used as matrix modifier. The ashing and the atomization temperature for Pb were 400 ℃ and 2 100 ℃, and for Cd were 250 ℃ and 1 800 ℃ respectively. Linear relationships between values of absorbance and mass concentration of Pb and Cd were obtained in the ranges of 0.50-50.0 and 0.10-2.5 μg·L-1, with detection limits of 6.5 and 0.4 pg, respectively. Four CRM′s of soil were analyzed by the proposed method, giving results in consistency with the certified values and values of RSD′s (n=6) in the ranges of 1.5%-6.3% for Pb and 2.3%-5.1% for Cd. Values of recovery obtained by standard addition method were found in the range of 85.4%-103.2% for Pb and 91.5%-102.3% for Cd.