GFAAS Determination of Cadmium in Soil

The soil sample was digested and heated with a mixture of HCl, HNO₃, HClO₄ and HF, and the content of cadmium in sample solution was determined by GFAAS. The 10 g·L^-1 NH₄H₂PO₄ solution was used as matrix modifier, and temperatures selected for ashing and atomization were 700℃ and 1 450℃ respectively. Linear relationship between values of absorbance and mass concentration of cadmium was obtained in the range of 0.2-1.6 μg·L^-1, with detection limit (3s) of 0.008 mg·kg^-1. The soil reference materials were determined for 12 times, giving values of RSDs in the range of 4.1%-4.9% and RE in the range of 2.5%-4.7%, respectively. The proposed method was used in the analysis of site investigation soil sample, and the results were in good agreement with those obtained by inductively coupled plasma mass spectrometry (ICP-MS).