Nondestructive X-ray fluorescence spectrometry for determination of trace elements along a single strand of hair.

Concentrations of trace elements in hair are finding increasing value in nutritional studies (essential trace elements) and in toxicology (toxic metals). Previously available methods have been tedious, time-consuming, and expensive. A new development in X-ray fluorescence instrumentation that provides automatic longitudinal scanning for some 16 elements in consecutive hair segments is discussed. The mass (in ..mu..g/mm) is determined simultaneously at each point, and the absolute concentrations are computed in parts per million for the elements. The method is nondestructive, and results (including mass) show much reproducible detail. The millimeter by millimeter longitudinal analysis allows recapitulation for previous toxic metal exposures for months or years, depending upon the length of the hair strand. This instrument, in a clinical setting, opens up many new research opportunities.