Preparation of fingernails for trace element analysis.

There are substantial differences in the reported elemental composition of human nails. Most investigators have used extensive washing procedures to minimize environmental contamination, however, such washing poses the risk of extraction of elements bound to the nail matrix. To determine if a portion of this variability could be accounted for by the "washing solutions" used by different investigators, nails were washed in nine solvents previously used for cleaning nails and their residual elemental composition measured by atomic absorption spectroscopy or energy dispersion analysis. In general, treatment with organic solvents resulted in less elemental loss than did treatment with aqueous detergents, while aqueous acids caused the greatest loss. Organic solvents more readily extracted iron and magnesium than calcium, copper and zinc. Virtually all of the magnesium was extracted by distilled water or aqueous detergents.