Abstract: A method for the direct analysis of analyte indicative of marijuana exposure found in keratinized structures, e.g., hair, fingernails and toenails, which comprises preparing a mixture containing dithiothreitol or dithioerythritol, a protease suitable for the digestion of the keratin structure and a sample of the keratin structure; permitting the enzyme to at least substantially digest the sample of keratin structure to form a digest solution, followed by mixing the digest solution with a suspension of an ion exchange resin to remove an interfering, cross reacting substance naturally found in hair and finally subjecting the digest solution to analysis to determine the identity and amount of marijuana analyte in the keratin structure sample. To accelerate the method, cupric sulfate may be added to the mixture after degradation of the keratin sample in order to deactivate the activator. The enzyme may be a protease with papain, chymopapain, and proteinase K being preferred for use in the invention.

Abstract: A method for the direct analysis of analyte in keratinized structures, e.g., hair, fingernails and toenails, which comprises preparing a mixture containing a low redox potential compound such as dithiothreitol or dithioerythritol, an enzyme suitable for the degradation of the keratin structure and a sample of the keratin structure; permitting the enzyme to at least substantially degrade the sample of keratin structure, and subjecting the mixture to analysis to determine the identity and amount of analyte in the keratin substance sample. To accelerate the method, cupric sulfate or sodium arsenite 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.