Heated Slurry Sampling for the Determination of Cadmium in Food by Electrothermal Atomic Absorption Spectrometry

A heating procedure is reported with slurry sampling electrothermal atomic absorption spectrometry to improve the accuracy of cadmium determination in food. In comparison to conventional slurry sampling, the heating significantly increased cadmium recovery and improved the precision. For the optimized procedure, 25-250mg of food were treated with 2% HNO3 and 1% H2O2 with heating at 120 degrees C for 20min, followed by the addition of 50 mu L of 10% Triton X-100, and homogenization in an ultrasonic bath prior to analysis. Tungsten and rhodium were employed as a permanent modifier with optimum pyrolysis and atomization temperatures of 500 degrees C and 1500 degrees C. Calibration with aqueous standards resulted in good agreement between certified or information values and measured results at the 95% confidence level. A characteristic mass of 0.8 +/- 0.1 pg and a detection limit of 0.7ngg(-1) for a 2% slurry were obtained. The method was employed for the direct determination of cadmium in food certified reference materials.