Determination of hydroxy metabolites of cocaine from hair samples and comparison with street cocaine samples.

Drugs which are commonly smoked or sniffed (e.g. cocaine), can contaminate hair through smoke or dust; therefore testing for metabolites, especially hydroxy metabolites, is highly recommended. The presence of hydroxy metabolites in street-cocaine (COC) has been discussed. To check if detection of hydroxy metabolites definitely proves ingestion, the presence of these metabolites in street COC samples has to be checked. It is expected that the more hydrophilic hydroxy metabolites of COC are incorporated into the hair-matrix to a lesser extent. For this study 576 COC positive hair samples (≥0.1ng COC/mg hair) were analysed by LC-MS/MS for benzoylecgonine (BE), norcocaine (NC), cocaethylene (CE), ortho-, meta- and para-hydroxy COC (o-, m-, p-OH-COC), meta- and para-hydroxy BE (m-, p-OH-BE), and meta- and para-hydroxy NC (m-, p-OH-NC). The results were compared with the respective metabolite/COC concentration ratios in 146 street COC samples, confiscated by the Bavarian police. Peak areas were used to estimate BE/COC, NC/COC, CE/COC and hydroxy metabolites/COC. Similar metabolic ratios were found for o-OH-COC in 88% of the samples, but for p-OH-COC and m-OH-COC only in 5.1% and 6.8%, respectively. Notably, p- and m-OH-BE as well as p- and m-OH-NC could not be identified from seized samples. We propose that area ratios exceeding the ratios of street COC more than twice or identification of OH-BE and OH-NC enable to differentiate COC consumption from contamination. Using these criteria, consumption of the drug could be proven in 92% of COC positive samples. As detection of meta- and para-hydroxy metabolites using the above mentioned criteria is a reliable tool to distinguish between ingestion and external contamination, it is recommended to implement their measurement into daily routine work.

Interpretation of forensic cases based on empirical data.

Over the course of the last years the importance of hair analysis increased obviously. For example work place testing, driving licence cases, so-called health checks, and especially in criminal acts the analysis of illicit substances is common. With the modern multiplex analytical methods (GC/MS, GC/MS/MS, LC/MS) the routine analytical probe of hair is in general unproblematic. But one of the major problems in hair analysis is the interpretation of the results. To solve this difficult and challenging task statistical data as a source of information could be a helpful tool. Examination of more than 1,000 hair segments within the past 2 years using gas chromatography/tandem-mass spectrometry (GC/MS/MS) as the preferred method for conducting the daily routine detection of the most prevalently abused drugs and metabolites, such as cannabinoids, cocaine, some synthetic drugs from the amphetamine group, and opiates serve as the basis for the statistics. The quantity of analytical results and additional essential facts have been documented in the publication to present our sources of information and supplementary data to prepare forensic reports.