Determination of methamphetamine in hair after single and repeated administration to rat.

Methamphetamine in hair after p.o. administration to rat was identified and determined by mass fragmentography (MF). Rat hair was washed with HCl/methnanol, methanol and water. The hair was crushed in 0.6 M HCl, suspension was alkalized with Na2CO3, and extracted with chloroform/isopropanol. The extract obtained was purified by column chromatography on aluminium oxide. Concentrated eluate was trifluoroacetylated, and methamphetamine was identified and determined by MF. More than 20 pg of methamphetamine was detectable and less than 1 ng of that was determined by MF. Methamphetamine in hair collected from rat after p.o. administration of 20 mg/kg of the drug was detected and determined up to 8 days after. From hair of rat after 5-days or 14-days repeated administration of 20 mg/kg/day, methamphetamine was detected 25 or 45 days after the last administration, respectively.