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- LC-MS/MS-MS3 for determination and quantification of ∆9-tetrahydrocannabinol and metabolites in blood samplesPublication . Proença, Paula; Martinho, Beatriz; Teixeira, Helena; Monteiro, Carla; Simões, Susana; Franco, João; Corte Real, F.Due to the high prevalence of cannabinoids in forensic toxicology, it is crucial to have an efficient method that allows the use of a small sample amount and that requires a minimal sample preparation, for the determination and quantification of low concentrations. A simple, highly selective and high throughput liquid chromatography tandem mass spectrometry method (LC-MS/MS-MS3) was developed for the determination and quantification of ∆9-tetrahydrocannabinol (THC), 11-hydroxy-∆9-THC (THC-OH) and 11-nor-∆9-THC-9-carboxylic acid (THC-COOH) in blood samples. Chromatographic analysis was preceded by a protein precipitation of 0.1 mL of blood samples with acetonitrile, then THC, THC-OH, THC-COOH and deuterated internal standards were separated on an Acquity UPLC® HSS T3 (100 mm x 2.1 mm i.d., 1.8 mm) reversed-phase column using a gradient elution with 2 mM aqueous ammonium formate (0.1% formic acid) and methanol, at a flow rate of 0.4 mL/min, and with a run time of 10 min. For MS/MS-MS3 analysis, a SCIEX QTRAP® 6500+ linear ion trap triple quadrupole mass spectrometer was used via electrospray ionization (ESI), operated in multiple reaction mode (MRM) and linear ion trap mode (MS3). The method was validated in accordance with international accepted criteria and guidelines. The method was selective and linear between 0.5-100 ng/mL (r2>0.995). The lower limits of quantification (LLOQ) corresponded to the lowest concentrations used for the calibration curves. The coefficients of variation obtained for accuracy and precision were less than 15%. The mean recoveries were between 88.0-101.4% for the studied concentration levels (1 ng/mL, 5 ng/mL and 50 ng/mL). No significant interfering compounds, matrix effects or carryover were observed. The validated method provides a sensitive, efficient and robust procedure for the quantitation of cannabinoids in blood using LC–MS/MS-MS3 and a sample volume of 0.1 mL. This work is also a proof of concept for using LC-MS3 technique to determine drugs in biological samples.
- Simultaneous analysis of some club drugs in whole blood using solid phase extraction and gas chromatography–mass spectrometryPublication . Castro, André Lobo; Tarelho, Sónia; Silvestre, Armando; Teixeira, Helena M.The use of psychoactive substances to improve social relations and increase body energy, in Rave Culture, has raised many legal and health public concerns, both for illicit trade and consumption. Therefore, forensic toxicology plays an important role in this area, mainly linked to the detection and quantitation of these substances, both in vivo and in post-mortem samples. In fact, at the moment, forensic sciences have been under public authorities’ scrutiny and critical look, due to the increasing attention of the media and public opinion, always applying for the use of scientific knowledge to help solving forensic cases. However, forensic toxicology results are only reliable to solve legal cases if all the analytical methodologies used are appropriately validated. In this work, a methodology for the extraction and analysis of 7-aminoflunitrazepam, buprenorphine, flunitrazepam, ketamine, methadone, phencyclidine (PCP) and d-propoxyphene was developed for whole blood samples, with Solid-Phase Extraction (SPE), using OASIS MCX SPE columns, and gas chromatography coupled to mass spectrometry. The procedure presented here proved to be reliable, specific, selective and sensitive, with good LODs and LOQs and good precision.The adoption of a SPE procedure with an automatic SPE extraction device, allowed an increased level of automation in sample treatment, being contemporarily less time-consuming, increasing productiveness, and allowing good recovery and appropriate selectivity being, also, simple and reproducible. The simultaneous detection and quantitation of all compounds by the same extraction and detection methodology is crucial and has a great potential for forensic toxicology and clinical analysis.
- Antidepressants detection and quantification in whole blood samples by GC–MS/MS, for forensic purposesPublication . Truta, Liliana; Castro, André Lobo; Tarelho, Sónia; Costa, Pedro; Sales, M. Goreti F.; Teixeira, Helena M.Depression is among the most prevalent psychiatric disorders of our society, leading to an increase in antidepressant drug consumption that needs to be accurately determined in whole blood samples in Forensic Toxicology Laboratories. For this purpose, this work presents a new gas chromatography tandem mass spectrometry (GC–MS/MS) method targeting the simultaneous and rapid determination of 14 common Antidepressants in whole blood: 13 Antidepressants (amitriptyline, citalopram, clomipramine, dothiepin, fluoxetine, imipramine, mianserin, mirtazapine, nortryptiline, paroxetine, sertraline, trimipramine and venlafaxine) and 1 Metabolite (N-desmethylclomipramine). Solid-phase extraction was used prior to chromatographic separation. Chromatographic and MS/MS parameters were selected to improve sensitivity, peak resolution and unequivocal identification of the eluted analyte. The detection was performed on a triple quadrupole tandem MS in selected ion monitoring (SIM) mode in tandem, using electronic impact ionization. Clomipramine-D3 and trimipramine-D3 were used as deutered internal standards. The validation parameters included linearity, limits of detection, lower limit of quantification, selectivity/ specificity, extraction efficiency, carry-over, precision and robustness, and followed internationally accepted guidelines. Limits of quantification and detection were lower than therapeutic and subtherapeutic concentration ranges. Overall, the method offered good selectivity, robustness and quick response (<16 min) for typical concentration ranges, both for therapeutic and lethal levels.