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PURPOSE: We developed and validated a method for quantitative analysis of ten synthetic cathinones in oral fluid (OF) samples, using microextraction by packed sorbent (MEPS) for sample preparation followed by liquid chromatography‒tandem mass spectrometry (LC‒MS/MS). METHOD: OF samples were collected with a Quantisal™ device and 200 µL was extracted using a C18 MEPS cartridge installed on a semi-automated pipette and then analyzed using LC‒M/SMS. RESULTS: Linearity was achieved between 0.1 and 25 ng/mL, with a limit of detection (LOD) of 0.05 ng/mL and a limit of quantification (LOQ) of 0.1 ng/mL. Imprecision (% relative standard deviation) and bias (%) were better than 11.6% and 7.5%, respectively. The method had good specificity and selectivity against 9 different blank OF samples (from different donors) and 68 pharmaceutical and drugs of abuse with concentrations varying between 400 and 10,000 ng/mL. No evidence of carryover was observed. The analytes were stable after three freeze/thaw cycles and when kept in the autosampler (10 °C) for up to 24 h. The method was successfully applied to quantify 41 authentic positive samples. Methylone (mean 0.6 ng/mL, median 0.2 ng/mL), N-ethylpentylone (mean 16.7 ng/mL, median 0.35 ng/mL), eutylone (mean 39.1 ng/mL, median 3.6 ng/mL), mephedrone (mean 0.5 ng/mL, median 0.5 ng/mL), and 4-chloroethcathinone (8.1 ng/mL) were quantified in these samples. CONCLUSION: MEPS was an efficient technique for Green Analytical Toxicology purposes, which required only 650 µL organic solvent and 200 µL sodium hydroxide, and the BIN cartridge had a lifespan of 100 sample extractions.

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No início dos anos 2000, as Novas Substâncias Psicoativas (NPS) emergiram de forma sem precedentes causando uma drástica mudança no mercado de drogas sintéticas mundial. Estas substâncias são sintetizadas para fins ilícitos e mimetizam o efeito psicoativo das drogas tradicionais. Até o momento, mais de 1000 substâncias foram reportadas mundialmente, representando um grande problema de saúde pública principalmente associado ao desconhecimento das suas propriedades toxicológicas. Por este motivo, métodos analíticos para detectar e quantificar estas substâncias em materiais biológicos são importantes nos casos de toxicologia analítica e forense. Contudo, a tendência de reduzir o impacto ambiental destas metodologias tem ganhado popularidade com a Toxicologia Analítica Verde (GAT). Portanto, o objetivo do presente trabalho foi desenvolver novas técnicas analíticas para analisar as principais classes de NPS em amostras biológicas enquanto aplicando os princípios sustentáveis estabelecidos pela GAT. Os resultados obtidos no presente trabalho são apresentados como coletânea de artigos científicos publicados em revistas. Estes estão descritos nos capítulos 4 a 8. No capítulo 4, uma revisão sobre os desafios no desenvolvimento de técnicas de preparo de amostra para fins forenses é abordada com foco no uso das matrizes secas. No Capítulo 5, está descrito a aplicação da microextração líquido-líquido dispersiva para catinonas sintéticas em amostras de sangue total e urina. No capítulo 6, o artigo descreve o desenvolvimento da técnica microextração líquido-líquido homogênea com solventes de hidrofilicidade comutável para canabinoides sintéticos em amostras de plasma. No capítulo 7, a microextração em fase líquida em placas de 96 poços, cunhada extração paralela em membranas artificiais líquidas, foi desenvolvida para diferentes classes de drogas de abuso, incluindo NPS. O capítulo 8 mostra o desenvolvimento de uma extração por eletromembrana também no formato de placa de 96 poços para catinonas sintéticas em amostras de sangue total. Em todos os trabalhos, as técnicas de extração foram desenvolvidas, otimizadas e validadas. Os princípios da GAT foram aplicados de diferentes formas, como reduzindo o volume de amostra, simplificando os procedimentos, evitando o uso de solventes orgânicos, dentre outros. Assim, alternativas mais sustentáveis para a análise de drogas de abuso em amostras biológicas foram apresentadas e estas ajudam a consolidar e difundir o conceito do desenvolvimento de métodos analíticos com consciência ambiental além de fornecer ferramentas para auxiliar o controle das NPS no país

In the early 2000s, New Psychoactive Substances (NPS) emerged and unprecedentedly changed the illicit drug market. These substances are synthesized for illicit purposes and mimic the psychoactive effect of traditional drugs of abuse. To date, more than 1000 substances have been reported worldwide, representing a major public health problem mainly associated with their mostly unknown toxicological properties. In this context, analytical methods able to detect and quantitate these new drugs in biological specimens are important in cases of analytical and forensic toxicology. However, reducing the environmental impact of these methodologies has recently gained popularity with Green Analytical Toxicology (GAT). Therefore, the aim of this work was to develop new analytical techniques to analyze the main classes of NPS in biological samples while applying the environmentally friendly principles established by GAT. The results obtained throughout the development of the present work were split into four papers (chapters 4-8). In chapter 4, a review of common challenges faced during the development of new sample preparation techniques for forensic applications is described focusing on the use of dried matrices. In chapter 5, the application of dispersive liquid-liquid microextraction for synthetic cathinones in whole blood and urine samples is described. In chapter 6, the application of the somewhat recent switchable hydrophilicity solvent-based homogenous liquidliquid microextraction to synthetic cannabinoids in plasma samples is reported. In chapter 7, liquid-phase microextraction in the 96-well plate format, termed parallel artificial liquid membrane extraction, for different classes of drugs of abuse, including NPS, in plasma samples is presented. In chapter 8, an electromembrane extraction in the 96-well plate format for synthetic cathinones in whole blood samples was developed. In this work, sample preparation techniques were developed, optimized and validated. The principles of sustainable chemistry in method development were applied in different ways, such as reducing the sample volume, simplifying procedures, avoiding the use of organic solvents, among others. Thus, greener alternatives were presented for the analysis of drugs of abuse in biological samples and contribute to consolidate and spread this trend of environmental consciousness during method development. Additionally, valuable techniques that can be used in the combat against NPS were provided

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Mephedrone (MEP) is an illicit stimulant drug that belongs to the synthetic cathinone (SC) class, which has been widely used for recreational purposes and reported in forensic analysis. The preliminary identification of MEP and other SCs in seized samples is of great interest for forensic investigation and a fast and simple screening test for these drugs would be useful for on-site and in-house analyses. In this study, we present the electrochemical detection of MEP in forensic samples using, for the first time, independent redox processes of SCs on a graphene screen-printed electrode (SPE-GP). The proposed method for MEP detection on the SPE-GP was optimized in Britton-Robinson buffer solution (0.1 mol L-1) at pH 10.0 with adsorptive stripping differential pulse voltammetry (AdSDPV). The use of the SPE-GP with AdSDPV provides a wide linear range for MEP determination (2.6 to 112 µmol L-1) with a low limit of detection (LOD) (0.3 µmol L-1). The real surface area available for adsorption on the SPE-GP was estimated to be between 3.80 and 5.70 cm2, which provided high sensitivity for the proposed method. Furthermore, good stability of MEP electrochemical responses on the SPE-GP was obtained using the same or different electrodes (N = 3), with relative standard deviation (RSD) < 5.0% for both redox processes. Interference studies for a common adulterant (caffeine) and twelve other illicit drugs (phenethylamines, amphetamines, and other SCs) were performed with a highly selective response for MEP detection. Therefore, the SPE-GP with AdSDPV is demonstrated to be a selective and sensitive screening method to detect MEP and other SCs in forensic analysis, providing a fast and simple preliminary identification of these drugs in seized samples.

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The present work describes a practical application of Green Analytical Toxicology (GAT) during the development of an eco-friendly dispersive liquid-liquid microextraction (DLLME) avoiding the use of highly toxic chlorinated solvents that are commonly used in this type of the technique. The purpose was to further consolidate GAT guidelines during method development. Thus, a full method optimization using a multivariate statistical approach and validation were performed. To that end, synthetic cathinones (SCs), one of the major classes of new psychoactive substances, were the target analytes due to their relevance and chemical diversity. Furthermore, whole blood and urine samples were the matrices of choice due to their clinical relevance. The sample preparation step prior to DLLME consisted of protein precipitation of whole blood samples, while urine specimens were centrifuged and diluted with ultrapure water. Then, borate buffer, sodium chloride and ethyl acetate:acetonitrile were added and vortexed. Finally, vials were centrifuged and the organic layer was transferred to autosampler vials, evaporated to dryness and resuspended with mobile phase prior to injection into the ultra-high performance liquid chromatography-tandem mass spectrometry system. Once optimized, the proposed DLLME was fully validated: 0.2 and 1 ng/mL as the limit of detection and 1 and 10 ng/mL as the limit of quantitation for urine and blood samples, respectively. The linear range was established as 1-100 and 10-1,000 ng/mL for urine and blood samples, respectively (r2 > 0.99), while the bias and precision were within acceptable limits (≥80%). The matrix effect was of 1.9-260.2% and -12.3-139.6%; while the recovery was of 27.4-60.0% and 13.0-55.2%; the process efficiency ranged from 45.0% to 192.0% and 17.9% to 58.4% for whole blood and urine, respectively. Finally, the method was applied to real case samples as proof of applicability. Thus, a simple, cheap and fast eco-friendly technique to analyze SCs in two biological specimens was described.

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Synthetic cathinones, often marketed as 'bath salts', have been reported to induce an excited delirium syndrome with characteristic symptoms such as paranoid, hallucination and even aggression. 3,4-Methylenedioxypyrovalerone (MDPV), a norepinephrine-dopamine reuptake inhibitor (NDRI), is one of the psychoactive ingredients in bath salts. The present study utilized cortical EEG and brain microdialysis in rats to compare the effects of MDPV (0.25, 1 and 2 mg/kg, i.p.) with the hallucinogenic drugs MK-801 (0.05, 0.1 and 0.5 mg/kg, i.p.) and ketamine (5, 15 and 25 mg/kg, i.p.). Results revealed that MDPV similar to MK-801 and ketamine caused a dose-dependent increase in the cortical EEG synchronization. In addition, all three drugs produced an increase in DA efflux in the prefrontal cortex (FCx). However, there existed difference between the three drugs. In contrast to MDPV, MK-801 and ketamine had only moderate or little effects on DA efflux in the nucleus accumbens (NAcc). Except for ketamine, the effects of MDPV and MK-801 on EEG synchronization were blocked by the D1 receptor antagonist SCH23990 (0.1 mg/kg, i.p.) and D2 receptor antagonist sulpiride (100 mg/kg, i.p.). SCH23990 or sulpiride had no effect on ketamine-induced increases in EEG synchronization. In summary, the present comparative studies suggest that DA in the FCx, but unlikely the NAcc, exerts a critical role in increasing EEG synchronization associated with the excited delirium syndrome. Neural circuits consisting of glutamatergic and GABAergic neurons responsible for the hallucinogenic effect are discussed in the context of hyperdopamine and dysconnection theories for hallucinatory behaviors.

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