Influence of bleaching on the enantiomeric disposition of amphetamine-type stimulants in hair

The aim of this work was to study the influence of hair bleaching on the enantiomeric ratios of amphetamine-type stimulants (ATS), including amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine and 3,4-methylenedioxyethylamphetamine. Hair specimens from 14 STA users were treated with a commercial bleaching product during 40 min. After alkaline digestion and solid-phase extraction of bleached and non-bleached hair, the STA enantiomers were derivatised with an in-house synthesised chiral reagent, the (2S,4R)-N-heptafluorobutyryl-4-heptafluorobutoyloxy-prolyl chloride. The diastereoisomers were quantified by GC/MS-NCI. The results showed that the concentrations of all enantiomers decreased in bleached hair in comparison with the non-treated hair (median values between 20 and 39%). The enantiomeric ratios of the STA in bleached hair were not significantly different from those determined in non-treated hair. Our findings pointed out that bleaching treatments decrease concentrations of STA in hair without influencing their enantiomeric ratios.