Application of solid-phase extraction for the analysis of drugs in biological matrices
Experimental mixed-mode solid-phase extraction columns of differing carbon number and carbon loading were investigated for the efficient extraction of drugs of abuse from biological matrices. Methadone and its two major metabolites (EDDP and EMDP) were chosen due to the increase in methadone drug-related deaths in the West of Scotland. Amphetamine and related compounds (methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methyleneidoxymethamphetamine (MDMA) and 3,4-methylenedioxyethylamphetamine (MDEA)) were chosen because of the prevalence of use of "speed" and "ecstasy" throughout the United Kingdom and the challenge these volatile drugs pose to the analyst. Improved methods were developed for the efficient extraction of methadone, EDDP and EMDP from whole blood and for amphetamine and related compounds from whole blood and hair. These methods were successfully applied to the analysis of postmortem samples. The stability of methadone, EDDP and EMDP in whole blood was investigated using the developed extraction method after sorting at various temperatures for a period of six months. Methadone remained stable in blood after six months. This was confirmed by the analysis of postmortem cases samples which when re-analysed within six months of the initial analysis, correlated well. Postmortem hair samples proved useful for determining antecedent drug use history whether extracted by solid-phase extraction or after screening with a Cohort enzyme immunoassay kit, adapted for hair analysis. Solid-phase extraction provides a clean and efficient means of extracting drugs of abuse from whole blood and hair. Simple manipulation of the extraction system (sample pretreatment, pH, derivatisation) provides a versatile alternative to lengthy liquid-liquid extraction techniques and has the added potential of automation.