Determination of cadmium in edible oils and fats by direct electrothermal atomic absorption spectrometry

Abstract

A method has been developed for the determination of the cadmium content in edible oils and fats by ETAAS using palladium as a chemical modifier. The samples heated at 60 ± 5 °C in a modified sample tray are injected directly into the graphite tube without prior sample pre-treatment. The influence of chemical modifiers (lecithin, niobium, organic and inorganic palladium compounds) and graphite tubes (pyrolytic graphite coated and uncoated graphite tubes with and without a platform) on the maximum pyrolysis temperature, sensitivity, background absorption and atomization signal shape were studied. Optimum performance was obtained with a palladium chloride modifier and uncoated graphite tubes with a pyrolytic graphite coated platform at a pyrolysis temperature of 750 °C and an atomization temperature of 1350 °C. The characteristic mass is 0.9 pg, the detection limit is 0.4 µg kg^–1 and the short-term and long-term precisions are 3 and 6%, respectively, at 6–10 µg kg^–1 of cadmium. A recovery of 101 ± 12% was found for different types of oils and fats.