Solid sampling graphite fibre felt electrothermal atomic fluorescence spectrometry with tungsten coil atomic trap for the determination of cadmium in food samples

Abstract

A new solid sampling device and procedure for determination of trace cadmium in food samples by atomic fluorescence spectrometry was developed, which made use of a graphite fibre felt (GFF) as the vaporizer and a tungsten-coil (TC) as the cadmium trap. The procedure was optimized by changing temperature and gas atmosphere at vaporizing, trapping and releasing steps respectively. Under optimized conditions, cadmium in solid sample was vaporized with the matrix by GFF at about 1600 °C, then separated from the matrix by trapping on the TC at room temperature; finally, cadmium was released from TC at 2000 °C and directly determined by a non-dispersion atomic fluorescence spectrometer (AFS) without extra atomization. The detection limit (DL) of this procedure was shown to be 30 ng L⁻¹ (0.3 pg); the relative standard deviation (RSD) was less than 5% at 10 μg L⁻¹ (100 pg); and no significant interference was found within a 10% error range. The recoveries for some certified reference materials and the spiked recoveries for some food samples were all satisfied. Furthermore, the mechanism of this procedure was interpreted.