Percorrer por autor "Neng, Nuno R."
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- An accurate and precise liquid chromatography–tandem mass spectrometry method for the determination of six phosphatidylethanol homologues in whole blood with phospholipid interferences minimizedPublication . Maria, Marisa; Neng, Nuno R.; Berg, ThomasAlcohol consumption is associated with a wide risk of different diseases, injury and death, and has significant social and economic consequences worldwide. Phosphatidylethanol (PEth) is a group of promising direct alcohol biomarkers, with a significantly longer half-life in blood than ethanol, which can be measured to predict different drinking patterns, such as heavy- and social drinking. This study aimed to develop and validate an accurate and precise LC-MS/MS method for the determination of six PEth homologues in whole blood with minimal interference from unwanted phospholipids. Different organic solvent mixtures for liquid-liquid extraction were investigated to obtain satisfactory recovery of PEth homologues and removal of the lyso-phospholipids and other early eluting phospholipids. The mixture of heptane/2-propanol (80:20, v:v) gave lower phospholipid background and better signal/noise values for the PEth peaks. An LC-MS/MS TQ-S system from Waters was used for the instrumental analysis. The main part of unwanted phospholipids were separated from the PEth homologues on an Acquity BEH C18 column (50 × 2.1 mm ID, 1.7 µm particles) using a buffer-free mobile phase of 0.025 % ammonia in Type 1 water, pH 10.7, as solvent A and methanol as solvent B. Validation and quantification of 22 authentic blood samples showed that the developed LC-MS/MS method is sensitive, precise and accurate for the determination of the six PEth homologues in whole blood. Lower limit of quantification was 10 nM for all compounds. No matrix effects were observed, possibly due to the successful strategies incorporated to avoid the influence of unwanted phospholipids.
- Application of bar adsorptive microextraction for the determination of levels of tricyclic antidepressants in urine samplesPublication . Oliveira, Mariana N.; Gonçalves, Oriana C.; Ahmad, Samir M.; Schneider, Jaderson K.; Krause, Laiza C.; Neng, Nuno R.; Caramão, Elina B.; Nogueira, José M. F.This work entailed the development, optimization, validation, and application of a novel analytical approach, using the bar adsorptive microextraction technique (BAμE), for the determination of the six most common tricyclic antidepressants (TCAs; amitriptyline, mianserin, trimipramine, imipramine, mirtazapine and dosulepin) in urine matrices. To achieve this goal, we employed, for the first time, new generation microextraction devices coated with convenient sorbent phases, polymers and novel activated carbons prepared from biomaterial waste, in combination with large-volume-injection gas chromatography-mass spectrometry operating in selected-ion monitoring mode (LVI-GC-MS(SIM)). Preliminary assays on sorbent coatings, showed that the polymeric phases present a much more effective performance, as the tested biosorbents exhibited low efficiency for application in microextraction techniques. By using BAμE coated with C18 polymer, under optimized experimental conditions, the detection limits achieved for the six TCAs ranged from 0.2 to 1.6 μg L−1 and, weighted linear regressions resulted in remarkable linearity (r2 > 0.9960) between 10.0 and 1000.0 μg L−1. The developed analytical methodology (BAμE(C18)/LVI-GC-MS(SIM)) provided suitable matrix effects (90.2–112.9%, RSD ≤ 13.9%), high recovery yields (92.3–111.5%, RSD ≤ 12.3%) and a remarkable overall process efficiency (ranging from 84.9% to 124.3%, RSD ≤ 13.9%). The developed and validated methodology was successfully applied for screening the six TCAs in real urine matrices. The proposed analytical methodology proved to be an eco-user-friendly approach to monitor trace levels of TCAs in complex urine matrices and an outstanding analytical alternative in comparison with other microextraction-based techniques.
- Bar adsorptive microextraction approach for trace determination of local anesthetics in urine matricesPublication . Pereira, Joana R. P.; Rocha, Daniela C.; Neng, Nuno R.; Maurício, Paulo; Torres, M. Edite; Ahmad, Samir M.; Quintas, AlexandreThe present work reports the development, optimization, and validation, of a methodology to determine lidocaine, procaine, tetracaine, and benzocaine in urine matrices. Two extractive preconcentration techniques, solid-phase microextraction (SPME) LC Tips and bar adsorptive microextraction (BAμE), were studied and applied to the four target anesthetics, followed by gas chromatography-mass spectrometry (GC-MS) analysis. Several parameters that could affect microextraction and back-extraction were optimized using two different designs of experiments (Box–Behnken and full-factorial) to maximize extraction efficiency from aqueous media. Under optimized experimental conditions, the BAμE technique showed better performance than SPME LC Tips and was chosen for validation assays and urine sample analysis. In blank urine, the BAµE/GC-MS methodology revealed suitable sensitivity (LOD between 2 and 18 ng/mL), good linearity (r2 ≥ 0.9945) between 0.5 and 30.0 µg/mL and recovery yields of 30.3–97.9%. Good precision (%RSD ≤ 8.8%) and accuracy (bias % between −15.9 and 15.0%) values were achieved. The developed methodology was successfully applied to the target anesthetics analysis of volunteers’ urine matrices and proved to be an environmentally friendly alternative to monitor trace levels of local anesthetics in complex matrices compared to other extraction techniques.
- Bar adsorptive microextraction coated with carbon-based phase mixtures for performance-enhancement to monitor selected benzotriazoles, benzothiazoles, and benzenesulfonamides in environmental water matricesPublication . Ahmad, Samir M.; Calado, Bruno B.C.; Oliveira, Mariana N.; Neng, Nuno R.; Nogueira, J.M.F.In the present work we propose, for the first time, bar adsorptive microextraction coated with carbon-based phase mixtures, followed by microliquid desorption and high performance liquid chromatography-diode array detection (BAμE-μLD/HPLC-DAD) analysis, to enhance the performance of the determination of traces of benzotriazoles (BTRs), benzothiazoles (BTs), and benzenesulfonamide derivatives (BSDs) in environmental water matrices. Assessing six carbon-based sorbents (CA1, CN1, B test EUR, SX PLUS, SX 1, and R) with different selectivity properties allowed us to tailor the best phase mixture (R, 12.5%/CN1, 87.5%) that has convenient porosity, texture, and surface chemistry (pHPZC,mix ~6.5) for trace analysis of benzenesulfonamide, 1-hydroxybenzotriazole, 1H-benzotriazole, 5-methyl-1H-benzotriazole, benzothiazole, and 1,3-benzothiazol-2-ol chemicals in aqueous media. Optimized experimental conditions provided average recoveries ranging from 37.9% to 59.2%, appropriate linear dynamic ranges (5.0 to 120.0 µg L−1; r2 ≥ 0.9964), limits of detection between 1.0 and 1.4 μg L−1, and good precisions (relative standard deviation (RSD) ≤ 9.3%). The proposed methodology (BAμE(R, 12.5%/CN1, 87.5%)-μLD/HPLC-DAD) also proved to be a suitable sorption-based static microextraction alternative to monitor traces of BTRs, BTs, and BSDs in rain, waste, tap, and estuarine water samples. From the data obtained, the proposed approach showed that the BAμE technique with the addition of lab-made devices allows users to adapt the technique to use sorbents or mixtures of sorbents with the best selectivity characteristics whenever distinct classes of target analytes occur simultaneously in the same application.
- Bar adsorptive microextraction for trace determination of natural and semi-synthetic cannabinoids in salivaPublication . Pereira, Maria Beatriz; Sá, Joana M. N.; Justino, Gonçalo C.; Quintas, Alexandre; Neng, Nuno R.Cannabis is the most widely consumed illicit substance worldwide, and the rise of synthetic and semi-synthetic cannabinoids poses growing public health concerns due to their high potency and unpredictable effects. This study presents a new analytical methodology for the simultaneous determination of natural and semi-synthetic cannabinoids (cannabidiol (CDB), Δ8-tetrahydrocannabinol (∆8-THC), Δ9-tetrahydrocannabinol (∆9-THC), and hexahydrocannabinol (HHC)) in saliva using gas chromatography coupled with mass spectrometry (GC-MS) in combination with bar adsorptive microextraction (BAμE) as a green sample preparation. The optimized method showed satisfactory recoveries (57.3–80.6%), low detection and quantification limits (1.25 and 4.13 ng/mL, respectively), excellent linearity (r2 ≥ 0.9963), and robust precision and accuracy. Application to authentic saliva samples demonstrated cannabinoid levels consistent with literature values. Overall, the proposed methodology offers a cost-effective, miniaturized, and environmentally sustainable platform for routine oral fluid cannabinoid analysis, highlighting its potential for forensic, clinical, and toxicological applications.
- Collaborative harm reduction efforts lead to the first detection of 5-cyano isotodesnitazene in illicit street drugsPublication . Barra, Bárbara F. C.; Pereira, Joana R. P.; Ferreira, Daniela R.; Oeri, Hans; Martins, Daniel; Almeida, Rui M.; Oatley, Giles; Neng, Nuno R.; Gaspar, Helena; Quintas, AlexandreIn the ongoing opioid crisis, regulatory restrictions on fentanyl and its derivatives have led to the emergence of nitazenes, a class of highly potent synthetic opioids synthesised during the 1950s but never approved for medical use. Structurally distinct from traditional opioids, nitazenes have gained increasing presence in illicit drug markets since 2019, contributing to a growing number of drug-related deaths across Europe, North America, and Australia. The rapid proliferation of novel nitazene analogues presents a significant challenge to law enforcement and public health systems. Drug-checking services (DCS) are currently one of the most effective tool for early detection and response, enabling real-time surveillance and consequently reducing the impact of overdoses due to Novel Synthetic Opioids. As a complement, universities can provide the scientific expertise and infrastructure necessary to confirm molecules detected by DCS. This study is the first report identifying and confirming 5-cyano isotodesnitazene in a street-sold drug, through an international collaboration involving two DCSs and three academic institutions. The structural elucidation was achieved through complementary analytical techniques comprising gas chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. The present work highlights the essential role that cross-sector cooperation and analytical innovation play in tackling the rapidly evolving threat of novel synthetic opioids.
- Comprehensive chemical and enantiomeric characterization of commercial turpentine oils by GC–MSPublication . Pombo, Débora․S․ D․; Barra, Bárbara F․ C․; Bettencourt, Madalena; Quintas, Alexandre; Bekman, Evguenia P.; Neng, Nuno R.Recent reports from families of individuals with Angelman syndrome (AS), a rare neurodevelopmental disorder characterised by severe neurological impairment and epilepsy, have described perceived neurological improvements following the topical application of a commercial turpentine oil (TO). These observations prompted the present analytical study, which aimed to characterise and quantify the terpenoid composition of 2 commercial TOs (Diamond and Creekwood), together with 6 additional commercial TOs, using gas chromatography-mass spectrometry (GC–MS). Analysis of 6 TOs reported to originate from Pinus pinaster revealed similar combined percentages of α- and β-pinene (≈75%), except for one oil that exhibited a more complex profile, a lower α-pinene content (≈30%), and the presence of eucalyptol, which is uncommon in TOs from this species. The Creekwood oil contained a higher proportion of α-pinene (≈76%) and a markedly lower β-pinene content (≈3%) than the Diamond oil (≈62% and ≈26%, respectively). Chiral GC–MS analysis further revealed contrasting enantiomeric distributions, with (–)-α-pinene predominating in the Diamond oil and (+)-α-pinene in the Creekwood oil, while (–)-β-pinene predominated in both samples. For quantitative analysis, the analytical method was successfully validated, demonstrating suitable detection (1.5–5.0 mg/L) and quantification (5.0–16.7 mg/L) limits, good linearity (r2>0.991), and acceptable precision and accuracy (<15%). These findings demonstrate substantial chemical variability among commercial TOs and provide a framework for future studies on the biological effects of pine resin terpenoids in neuronal models relevant to AS.
- Determination of dextromethorphan and dextrorphan in urine using bar adsorptive microextraction followed by gas chromatography : mass spectrometry analysisPublication . Maria, Marisa H.; Fonseca, Margarida; Quintas, Alexandre; Neng, Nuno R.Over the past few years, the misuse of medications has progressively increased, posing a significant public health concern. This study proposed the development and validation of an alternative and greener analytical method for the determination of dextromethorphan (DXM) and its major metabolite, dextrorphan (DXO), in urine matrices using bar adsorptive microextraction (BAμE), followed by gas chromatography–mass spectrometry (GC-MS) analysis. Under optimized experimental conditions, average recoveries of 96.3% and 80.4% were achieved for DXM and DXO, respectively. The analytical limits obtained were 0.016 μg/mL for the limit of detection and 0.054 μg/mL for the limit of quantification. The working range was from 0.06 μg/mL to 2.0 μg/mL, with linearity for both compounds by determination coefficients (r2 > 0.99) and the goodness-of-fit and lack-of-fit tests. Intra-day precision and trueness yielded values below 8.77% and 16.28%, respectively, for both compounds. Inter-day precision and trueness values were below 7.67% and 9.73%, respectively. The application to 26 urine samples allowed the quantification of both compounds, with concentrations ranging from 0.06 to 3.21 μg/mL for DXM and 0.06 to 8.88 μg/mL for DXO. The method proved to be effective, selective, sensitive, simple, and cost-effective in the detection and quantification of DXM and DXO, reinforcing its applicability and feasibility in various laboratory contexts.
- Development and validation of a simple and fast method for routine analysis of new synthetic opioids and hallucinogens in whole blood using protein precipitation and UHPLC-MS/MSPublication . Pereira, Joana R. P.; Antunes, Mónica; Neng, Nuno R.; Mustra, Carla; Franco, João; Fonseca, SuzanaIn forensic toxicology, the rapid and reliable detection of emerging synthetic opioids and hallucinogens is crucial for case investigations and public health monitoring. This work describes the development, optimization and validation of a simple, fast and sensitive methodology for the simultaneous analysis of 6 new synthetic opioids (carfentanil, fentanyl, isotonitazene, metonitazene, norfentanyl, and sufentanil) and 2 hallucinogens (lysergide [LSD] and mescaline), together with the main LSD metabolite 2-oxo-3-hydroxy-lysergide [LSD-OH], in whole blood samples by liquid chromatography coupled to tandem mass spectrometry. Under optimized experimental conditions, linearity was verified between 0.1 and 20 ng/mL for all analytes except mescaline (2.5–500 ng/mL), with r2 > 0.99 for 1/x weighting, and no significant carryover or matrix effects were observed. Good precision (% RSD < 13 %) and trueness (% Bias within ± 20 %) values were achieved. The estimated limit of quantification (LOQ) was 0.1 ng/mL for all compounds except mescaline (2.5 ng/mL). Authentic forensic samples were also analyzed, and positive samples for fentanyl, norfentanyl, and sufentanil were identified. The proposed methodology allows the simultaneous analysis of compounds from different families of psychoactive substances, in both postmortem and in vivo samples, using only 50 µL of whole blood. The demonstrated speed, simplicity, and effectiveness make it particularly advantageous for routine implementation in forensic toxicology laboratories.
- Development of green approaches for preconcentration of local anesthetics in biological matricesPublication . Pereira, Joana; Rocha, Daniela C.; Neng, Nuno R.; Torres, M. Edite; Quintas, Alexandre; Ahmad, Samir M.Poster presented at the CQE Days - 5º encontro anual do Centro de Química Estrutural do Instituto Superior Técnico da Universidade de Lisboa. Lisboa, 25-26 may 2023
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