Direct Determination of Cadmium in Grain by Solid Sampling Electrothermal Vaporization Atomic Fluorescence Spectrometry with a Tungsten Coil Trap

A simple and rapid method was developed for the determination of cadmium in grain. Porous carbon was employed as an electrothermal vaporizer with a sampling boat for atomic fluorescence spectrometry with on-line ashing to eliminate matrix interferences. Grain was pulverized to a particle size less than 0.25mm to provide good homogeneity. Pauwels' equation was employed to determine that the minimum sample mass was approximately 2mg. Optimal conditions for ashing (90W and 50s), vaporization (110W and 20s), and argon-hydrogen flow (0.6L/min) were determined. Under the optimized conditions, the limit of quantification was 0.11 mu g/kg, and the relative standard deviation was less than 10%. Furthermore, the mean fortified recovery in grains was between 83.5 and 107.7% (n=6). To validate the method, cadmium was also determined in these samples by ICP-MS, and there were no significant differences between the results using the methods.