Abstract
A rapid and precise method for the determination of microamounts of cadmium, copper, nickel and manganese in fats and oils has been studied. The samples were decomposed by wet-digestion procedure using sulfuric acid and hydrogen peroxide (30%), then, cadmium and other metals in the decomposed solution were extracted into methyl isobutyl ketone as the complexes with sodium diethyldithiocarbamate. The extracts were directly atomized into the air-acetylene flame, and the absorbances were measured at 228.8nm for cadmium, 324.7nm for copper, 232.0nm for nickel and 279.5nm for manganese. The most suitable pH for the extraction of these metals was about 7, and these metals were quantitatively extracted into methyl isobuthyl ketone by once extraction.
The proposed method was evaluted with respect to recovery and reproducibility by carring out collaborative studies on the samples which were prepared by adding known amounts of cadmium and other metals to soybean oil. The results thus obtained showed good agreement with the theoretical values and satisfactory reproducibility.
