Metallic contamination of food during preparation and storage: Development of methods and some preliminary results.

A chemical procedure for studying trace metals leached from metallic cooking utensils and preserving cans used in the preparation and storage of food has been developed. The method consists in the destruction of the major part of organic matter with HNO3-vapour followed by a complete mineralization of residues with small amounts of HNO3 in Teflon bombs at 150-160°C under a pressure of 3-12 kg/cm2, depending on the amount and composition of the samples. Subsequently, an ion-exchange step removes major components and concentrates the trace elements in a dilute HNO3-solution, suitable for analysis. The ion-exchange separation, which is performed with an automatic ion-exchange separator, is practically free from blank level problems, e.g., typically a mean of less than 2% of the sample levels of the elements being determined. Preliminary results show that large amounts of aluminium are released from vessels to the water during boiling at the same pH-range which exists for most drinking water in Sweden

Some determinations of Hg, As, Se, Sb, Sn and Br in water plants, sediments and fishes in Bavarian Rivers.

Neutron activation analysis with chemical separation after irradiation was applied to the determination of some toxic elements, especially Hg, As, Se, Sb, Sn and Br in Bavarian Rivers. The chemical separation was a distillation method earlier described. The sampling places were sometimes chosen near to some plastics factories, using chlorine alkali electrolysis. The authors found concentrations of mercury in plants of up to 250 ppm dry weight and concentrations of tin up to 3000 ppm. The upper level of arsenic in river sediments was about 40 ppm, whereas selenium was present in higher concentrations than the other elements in some fishes, e.g. up to 18 ppm in eel livers