A CHEMICAL CLEANUP PROCEDURE TO REDUCE TRACE-METAL CONTAMINATION FROM LABORATORY BLENDERS

A simple and cost-effective method is described for minimising adventitious contamination from laboratory blenders prior to their use for the homogenisation of food samples that are to be analysed for mineral content. The blenders were treated with a hot aqueous solution of a mixture of 2% EDTA and 2% citric acid. The solution was allowed to mix in the blender at medium speed for a total period of 5 min before the bowls of the blenders were rinsed and the treatment repeated for a second time. A range of metals was determined from food samples homogenised in the treated blenders and the concentrations of metals were compared with those found in identical food samples homogenised in untreated blenders. Significant differences in metal level concentrations were observed for iron, zinc, copper, lead, cadmium and chromium - with the untreated blenders giving rise to a considerably higher degree of contamination. The results obtained indicate that laboratory blenders intended for homogenising food samples prior to analysis for metal content may need a chemical clean-up before use. The clean-up procedure described may provide a viable way of minimising contamination, particularly in the absence of specially modified equipment.