Abstract: A method the direct analysis of an analyte in keratinized structures, e.g., hair and fingernails, which comprises preparing a mixture containing a low redox potential activator compound such as dithiothreitol or dithioerythritol, an enzyme suitable for the digestion of the keratin structure, a sample of the keratin structure and a biological detergent that aids the digestion of the keratinized structure at a relatively low pH, e.g., between about 6.2 and 8; permitting the enzyme to at least substantially digest the sample of keratin structure, and subjecting the digest solution to analysis, preferably by radioimmunoassay, to determine the identity and amount of analyte in the keratin structure sample. To accelerate the method, cupric sulfate may be added to the mixture after degradation of the keratin sample. The enzyme may be a peptidase, endopeptidase or proteinase, with papain, chymopapain, and proteinase K being preferred for use in the invention.

Abstract: A method for the direct analysis of the presence of an analyte which becomes embedded in keratinized structures, e.g., hair, fingernails and toenails, from the bloodstream of a subject which comprises preparing a mixture containing dithiothreitol or dithioerythritol (“DTT”), an enzyme suitable for the digestion of the keratin structure and a sample of the keratin structure; permitting the enzyme to digest the sample of keratin structure to form a digest solution, followed by the addition of a salt of a metal of copper, zinc, manganese, iron, lead, cadmium, mercury, silver and cobalt to deactivate the DTT; and finally subjecting the digest solution to analysis to determine the presence of the analyte in the keratin structure sample. The protease enzymes papain, chymopapain, and proteinase K are preferred for use in the invention.

Abstract: A method for the direct analysis of the presence of an analyte which becomes embedded in keratinized structures, e.g., hair, fingernails and toenails, from the bloodstream of a subject which comprises preparing a mixture containing dithiothreitol or dithioerythritol ("DTT"), an enzyme suitable for the digestion of the keratin structure and a sample of the keratin structure; permitting the enzyme to digest the sample of keratin structure to form a digest solution, followed by the addition of a salt of a metal of copper, zinc, manganese, iron, lead, cadmium, mercury, silver and cobalt to deactivate the DTT; and finally subjecting the digest solution to analysis to determine the presence of the analyte in the keratin structure sample. The protease enzymes papain, chymopapain, and proteinase K are preferred for use in the invention.