Validation of a method to detect cocaine and its metabolites in nails by gas chromatography-mass spectrometry.

The objective of the present work was to compare previously published methods and provide validation data to detect simultaneously cocaine (COC), benzoylecgonine (BE) and norcocaine (NCOC) in nail. Finger and toenail samples (5mg) were cut in very small pieces and submitted to an initial procedure for external decontamination. Methanol (3 ml) was used to release analytes from the matrix. A cleanup step was performed simultaneously by solid-phase extraction (SPE) and the residue was derivatized with pentafluoropropionic anhydride/pentafluoropropanol (PFPA/PFP). Gas chromatography-mass spectrometry (GC-MS) was used to detect the analytes in selected ion monitoring mode (SIM). Confidence parameters of validation of the method were: recovery, intra- and inter-assay precision, as well as limit of detection (LOD) of the analytes. The limits of detection were: 3.5 ng/mg for NCOC and 3.0 ng/mg for COC and BE. Good intra-assay precision was observed for all detected substances (coefficient of variation (CV)<11%). The inter-assay precision for norcocaine and benzoylecgonine were <4%. For intra- and inter-assay precision deuterated internal standards were used. Toenail and fingernail samples from eight declared cocaine users were submitted to the validated method.

Detection of cocaine and cocaethylene in sweat by solid-phase microextraction and gas chromatography/mass spectrometry.

In the present work, a semi-quantitative method was developed to detect simultaneously cocaine (COC) and cocaethylene (CE) (transesterification product of the coingestion of COC with ethanol) in sweat. Sweat samples were collected by means of a non-occlusive sweat patch device supplied by PharmChek. The method was based on the dissolution of COC and CE incorporated into the patch, with 0.2 M sodium acetate buffer (pH 5.0) and the extraction of the analytes by solid-phase microextraction (SPME). Gas chromatography/mass spectrometry (GC-MS) was used to detect the analytes in selected ion monitoring mode (SIM). The method showed to be very simple, rapid and sensitive. The limits of detection were 5 ng/ml for COC and CE (12.5 ng/patch). Good inter and intra-assay precision was also observed (coefficient of variation <8%) with the use of deuterated internal standards.

Non-intentional doping in sports.

Compulsory drug testing was introduced in 1968 by the International Olympic Committee. Since then, several doping cases have been reported in sports competition world wide. Positive results are based on the detection of prohibited substances, their metabolites and markers in biological (mainly urine) samples supplied by athletes. In some cases, the evidences were not contested and athletes admitted the use of banned substances. However, in other cases, athletes denied the use of doping to enhance performance and claimed to have inadvertently or passively absorbed the drug. Unfortunately, no current accepted analytical method is capable of distinguishing between a sample from a cheater and one from an athlete who was passively exposed to a doping agent. Athletes' allegations have included the passive inhalation of drug smoke (e.g. marijuana) or the ingestion of food or products sold as nutritional supplements that contained prohibited substances. In the scientific literature, several studies have been performed to investigate the possibility of an accidental exposure being the reason for the appearance of detectable quantities of banned substances in urine samples. Based on these studies, this article discusses those cases where the athlete's claims could be possible in generating a positive result in doping control and in which circumstances it would be improbable to happen.

Determination of cocaine, benzoylecgonine and cocaethylene in human hair by solid-phase microextraction and gas chromatography-mass spectrometry.

The present work describes a highly precise and sensitive method developed to detect cocaine (COC), benzoylecgonine (BE, its main metabolite) and cocaethylene (CE, transesterification product of the coingestion of COC with ethanol) in human head hair samples. The method was based on an alkylchloroformate derivatization of benzoylecgonine and the extraction of the analytes by solid-phase microextraction (SPME). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring mode (SIM). The limits of quantification and detection (LOQ and LOD) were: 0.1 ng/mg for COC and CE, and 0.5 ng/mg for BE. Good inter- and intra-assay precision was observed. The dynamic range of the assay was 0.1-50 ng/mg. The method is not time consuming and was shown to be easy to perform.