Synthetic cannabinoids in hair - Pragmatic approach for method updates, compound prevalences and concentration ranges in authentic hair samples.

Since the first detection of synthetic cannabinoids (SCs) in so-called 'legal high' products (e.g. 'Spice') sold as legal alternatives to marihuana, the rapid development of this class of designer drugs poses a great challenge for analytical laboratories. The aim of this study was the comprehensive validation of an up-to-date LC-MS/MS method for detection of SCs in human hair for the purpose of drug abstinence testing and evaluation of a pragmatic re-validation approach for frequent method adaption. The validation demonstrated low quantification limits (0.5-5.0 pg mg-1) and acceptable selectivity, linearity, accuracy, and precision for 72 SCs. High matrix effects have been taken into consideration as a major limitation of the method. The partial re-validation approach proved to be an appropriate compromise between reduced validation effort and sufficient control of the method performance enabling analysts to keep pace with the dynamics of the drug market. The analysis of 294 authentic samples resulted in 163 positive samples and showed a broad concentration range (<1.0-5,700 pg mg-1) for 52 SCs in hair with up to 17 different compounds detected in a single hair sample. Periods of detection between one and 58 months were observed for single compounds in hair. Regarding the interpretation of analytical findings semi-quantitative concentrations were considered sufficient for a rough classification of the intensity of drug exposure in (i) passive exposure or exposure in the distant past (lower pg mg-1 range), (ii) more intense exposure (elevated concentration range, >20 pg mg-1 (upper 25th-percentile)), and (iii) heavy/recent exposure (>150 pg mg-1).

Immunoassay screening in urine for synthetic cannabinoids - an evaluation of the diagnostic efficiency.

BACKGROUND: The abuse of synthetic cannabinoids (SCs) as presumed legal alternative to cannabis poses a great risk to public health. For economic reasons many laboratories use immunoassays (IAs) to screen for these substances in urine. However, the structural diversity and high potency of these designer drugs places high demands on IAs regarding cross-reactivity of the antibodies used and detection limits. METHODS: Two retrospective studies were carried out in order to evaluate the capability of two homogenous enzyme IAs for the detection of currently prevalent SCs in authentic urine samples. Urine samples were analyzed utilizing a 'JWH-018' kit and a 'UR-144' kit. The IA results were confirmed by an up-to-date liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) screening method covering metabolites of 45 SCs. RESULTS: The first study (n=549) showed an 8% prevalence of SCs use (LC-MS/MS analysis) among inpatients of forensic-psychiatric clinics, whereas all samples were tested negative by the IAs. In a second study (n=200) the combined application of both IAs led to a sensitivity of 2% and a diagnostic accuracy of 51% when applying the recommended IA cut-offs. Overall, 10 different currently prevalent SCs were detected in this population. The results can be explained by an insufficient cross-reactivity of the antibodies towards current SCs in combination with relatively high detection limits of the IAs. CONCLUSIONS: In light of the presented study data it is strongly recommended not to rely on the evaluated IA tests for SCs in clinical or forensic settings. For IA kits of other providers similar results can be expected.