Abstract
A simple and rapid method is described for the direct determination of cadmium in the NBS bovine liver, SRM 1577 by Zeeman atomic absorption spectrometry using the graphite miniature-cup in conjunction with an electrothermal furnace of a crucible type.As cadmium is volatile element, the organic matrix was not completely decomposed at a fixed temperature.The residual matrix interfered with the linearity of calibration and the precision. Inorder to decompose the organic matrixes, a few kinds of acids were examined.An addition of 5 μl of 4 N-H2SO4 before the start ofthe thermal program showed the remarkable improvements in the linearity of calibration and the precision. The optimal thermal programs obtained were as follows: dried at 110 °C for 60 s, charred at 240 °C for 120 s, atomized at 2100 °C for 5 s, auto cleanedat 2250°C for 3 s. The cadmium calibration curves showed a good linearity of 00.14 ng. The absolute sensitivity i. e. cadmium weight which shows 0.0044 of absorbance, was 0.003 ng. The result of determination of cadmium in the NBS bovine liver by means of the standard addition method was 0.25 μg/g which was a good agreement with the certificated value { (0.27 ±0.04) μg/g}. The coefficient of variation for 14 measurements was 9.6 %.
