How do you pretreat hair samples?

Hair samples can first be washed with various solvents such as dichloromethane, methanol and water to remove external contamination.  After drying, the sample can be pulverized.  An acidic buffer such as 0.1 M HCl or extraction solvent such as methanol is then added to the pulverized sample to hydrolyze the sample and extract analytes of interest.  The mixture is incubated for a time period that could extend overnight.  This mixture is then centrifuged.  The resulting supernatant is neutralized as needed and can be dried down/reconstitute for analysis or undergo further cleanup such as SPE to eliminate matrix interferences prior to analysis.