Effect of washing procedures on trace-element content of hair

A pooled sample of hair was divided and portions prepared for analysis by three washing procedures, to evaluate the effect of washing procedure on the subsequent trace-element (Zn, Cu, Mg) content. The methods selected were a detergent wash, a hexane-ethanol wash, and an acetone-ether-detergent wash. For all elements, there was a significant difference among the results after these wash procedures. Magnesium content of hair was most affected by washing, containing less than half of the magnesium of the unwashed hair. The detergent wash removed the most zinc and magnesium; the acetone-ether-detergent wash removed the most copper. Our results indicate that the trace-element analysis of hair is sensitive to the preparation technique and therefore is an unreliable source of information about trace-element status.