Chapter 2 Current methods for the separation and analysis of cocaine analytes

SPE-UHPLC-ESI-MS/MS Analysis of Cocaine and Its Metabolites in Conventional and Alternative Biological Specimens: Application to Real Samples

An increase in cocaine abuse has been observed globally since the past decade. Cocaine is among the commonly abused stimulants used for recreational purposes. In this study, the SPE-UHPLC-MS/MS method was developed and validated to be applied on real specimens of 20 chronic cocaine abusers to quantify cocaine/metabolites in conventional as well as alternative biological matrices. Cocaine was extracted from biological specimens using solid-phase extraction followed by liquid chromatography tandem mass spectrometry analysis. Chromatographic separation was achieved on a Poroshell120EC-18 column (2.1 mm × 50 mm, 2.7 μm particle size) using water-acetonitrile in 0.1% formic acid as a mobile phase in gradient elution mode. The flow rate of the mobile phase was 0.5 mL/min with a gradient varying the percentage of acetonitrile linearity ranging 15-95% in 6.0 min acquisition time, and the injection volume was set at 5 μL. Positive electrospray ionization with multireaction ion monitoring mode using two ion transitions for cocaine/metabolites and one for cocaine-d3 was employed. The quantification method demonstrated good linear ranges of 0.025-250 ng/mL in blood, urine, and oral fluid (ng/mg for hair and nail) with a ≥0.991% determination coefficient. The detection limit and lower quantification limit were 0.005 and 0.025 ng/mL in all matrices, respectively. The mean extraction recovery and ionization suppression ranged from 89.3 to 99.8% and -4.6 to -14.4% in the studied matrices. Within-run and between-days precisions were 1.8-7.2% and 1.9-6.1%, respectively. This study will not only help in quantifying cocaine/metabolites in alternative specimens (hair, nail, and oral fluid) but also guide clinical and forensic toxicologists in interpretation of exhumation cases. Furthermore, multiple specimens' analyses can be of significance in estimating the time/manner of drug exposure, in confirming the results of laboratories in cases of doubtful clinical histories, or in aiding medico-legal investigations.

Determination of steroid hormones in grey seal (Halichoerus grypus) blood plasma using convergence chromatography tandem mass spectrometry

A hybrid solid phase extraction (HybridSPE) protocol tailored to ultra-performance convergence chromatography tandem mass spectrometry (UPC²-MS/MS) was developed for the determination of 19 steroid hormones in grey seal (Halichoerus grypus) blood plasma. In this study, the protocol demonstrated acceptable absolute recoveries ranging from 33 to 90%. The chromatographic separation was carried out using a gradient elution program with a total run time of 5 min. For most target analytes, the method repeatability ranged from 1.9 to 24% and the method limits of quantification (mLOQs) ranged from 0.03 to 1.67 ng/mL. A total of 9 plasma samples were analysed to demonstrate the applicability of the developed method, and 13 steroid hormones were quantified in grey seal pup plasma. The most prevalent steroids: cortisol, cortisone, corticosterone, 11-deoxycortisol, progesterone and 17α-hydroxyprogesterone were detected at concentrations in the range of 12.6-40.1, 7.10-24.2, 0.74-10.7, 1.06-5.72, 0.38-4.38 and <mLOQ - 1.01 ng/mL, respectively. To our knowledge, this is the first study to determine steroid hormones in the plasma of pinnipeds using convergence chromatography.

Development and validation of an ultra-performance liquid chromatography-tandem mass spectrometric method for the determination of 25 psychoactive drugs in cerumen and its application to real postmortem samples

PURPOSE

In the present study, a method for the detection of 25 psychoactive substances in cerumen was developed and validated. This method targets opiates, cocaine, antidepressants, benzodiazepines, antipsychotics and antiparkinsons.

METHODS

Analysis was performed on a SCIEX Triple Quad 6500+ system after liquid-liquid extraction. Methanol with 1% acetic acid was chosen as the extraction solvent. After the addition of the solvent, samples were vortexed, sonicated, centrifuged and directly injected into the liquid chromatography-tandem mass spectrometry system.

RESULTS

The method was found to be selective and sensitive (limit of detection: 0.017 ng-0.33 ng/mg), the assay was linear for all analytes with linear regression coefficient ranging 0.9911-1.00. The values for intra-assay precision was between 4.34 and 14.6% and inter-assay precision between 5.81 and 17.7%, with accuracy within the acceptable criteria for all analytes. All analytes in cerumen specimens were stable for 48 h at 4 °C and 72 h at - 20 °C, whilst no significant matrix effect or carryover was observed. Applicability was proven by analyzing cerumen samples from 25 deceased with a history of drug abuse. All analytes were detected in real samples, thus confirming the sensitivity of the developed method.

CONCLUSIONS

According to our knowledge, it is the first time that a method for the simultaneous detection of 25 psychoactive drugs in cerumen was developed, fully validated and finally applied to 25 postmortem samples.