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

Abstract

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 0.25 mm to provide good homogeneity. Pauwels’ equation was employed to determine that the minimum sample mass was approximately 2 mg. Optimal conditions for ashing (90 W and 50 s), vaporization (110 W and 20 s), and argon-hydrogen flow (0.6 L/min) were determined. Under the optimized conditions, the limit of quantification was 0.11 µg/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.