Assessment of chronic cocaine use by hair analysis: HPLC-F vs. LC-MS/MS

In the last few years, cocaine (methyl-3-(benzoyoxy)-8-methyl-8-azabicyclo[3.2.1]octa-ne-2-carboxylate) has been the topic of intense scientific research in order to better understand the mechanisms responsible for addiction, usage patterns and habits. Within this frame, hair analysis has an important role in establishing the chronic state of dependence. As a follow-up of a recently published study on the analysis of cocaina alone by HPLC-F, we now present two new analytical methods, based on LC-MS/MS and on HPLC-F, for the determination in hair of cocaine, its main metabolite benzoylecgonine and cocaethylene, the main metabolic product formed as a consequence of concomitant intake of cocaine and alcoholic beverages. By analysing these three compounds, important data can be obtained on usage patterns of two toxic substances, as is frequently the case with cocaine consumers. An innovative sample pre-treatment procedure, based on solvent incubation of the hair sample, grants good matrix purification. Fluorimetric detection resulted to be particularly advantageous, since all analytes are natively fluorescent and can thus be directly injected into the system after pre-treatment. The results of the two methods are always in agreement, with good precision and accuracy values. They have been successfully applied to hair samples from subjects suspected of cocaine and/or alcohol use and seem to be suitable for monitoring of chronic cocaine consumption.