Segmental analysis for cocaine and metabolites by HPLC in hair of suspected drug overdose cases

Hair samples of eight postmortem cases were analyzed in segments of 1 to 3 cm for cocaine, benzoylecgonine and cocaethylene. Samples were prepared for analysis by digestion in 0.1 M HCl and subsequent extraction with mixed-mo de solid-phase extraction columns, Measurement was made by reversed-phase, narrow-bore HPLC and fluorescence detection using two laboratory-made inter nal standards. The concentrations were in the region of 0.29-316 ng/mg of h air for cocaine, 0.43-141 ng/mg of hair for benzoylecgonine and 0.93-1.83 n g/mg of hair for cocaethylene. All eight investigated cases had cocaine-pos itive segments. In six of the cases, all segments were positive: suggesting regular cocaine use and two showed in-between negative segments indicating an interruption or a change of the abuse intensity. The results showed a s econd, remarkable observation, i.e, enormous concentration differences (fac tor > 150) for both cocaine and benzoylecgonine between the different subje cts. Furthermore, interindividual cocaine/benzoylecgonine ratios ranged fro m 0.02 to 8.33. We believe these observations could in part be attributed t o both some of the still existing limitations in the analytical approach(es ), especially the mandatory hair washing steps, and in our still too limite d knowledge of the hair incorporation processes. Nevertheless, in some case s, segmental analysis proved to be an important tool to distinguish, togeth er with postmortem examination, deadly chronic abuse from single acute drug overdosage. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.