A new clean-up approach for stomach content toxicological analysis

Post-mortem toxicological analysis of cocaine: main biological samples and analytical methods

This scoping review intends to identify the most used analytical methods and biological samples in the post-mortem forensic toxicological analysis of cocaine and its metabolites. A scoping review was performed based on the question "What are the analytical methods and types of biological samples most frequently used to identify and quantify cocaine in post-mortem forensic toxicology?" The studies were selected from five databases and, after exclusions, the data were tabulated, analyzed, and reported. Twenty-one articles published between 2012 and 2022 were filtered from five different databases to be studied. The collected data indicate that the most used biological samples were blood and hair. The most used sample preparation technique was solid phase extraction, while the most mentioned chromatography method was liquid chromatography with mass spectrometry. This review presents and discusses the state of the art regarding methods for the detection sensitivity spectrum, why limits of quantification are so important for these methods, and what are the most suitable biological samples to be utilized in each case. Cocaine and metabolites are important in forensic toxicologic post-mortem analysis. However, there is little concern in the development of miniaturized and automated sample preparation in this field. Besides, there is not enough understanding of post-mortem redistribution, tolerance, drug-drug interactions, and pre-existing medical conditions.

Target analysis of psychoactive drugs in oral fluid by QuEChERS extraction and LC-MS/MS

This study aimed to validate a modified QuEChERS method, followed by liquid chromatography-tandem mass spectrometry, for the determination of 51 psychoactive substances and screening of 22 ones in oral fluid from electronic dance music party (EDM) attendees. Unstimulated oral fluid was collected in a polypropylene tube and stored in a glass vial at -20 ºC. The sample was extracted with acetonitrile:water and MgSO4/NaOAc, followed by cleanup with primary secondary amine and MgSO4. The effectiveness of the sample storage conditions was shown to be comparable to when the Quantisal™ buffer was used, with no substantial concentration loss (< 15%) for all the substances after up to 72 hours at -20º C. The method was satisfactorily validated, with limits of detection (LOD) and quantification (LOQ) ranging from 0.04 to 0.5 ng/mL and 0.1-1.5 ng/mL, respectively, and was applied to the analysis of 62 real samples. The main substances detected were 3,4-methylenedioxymethamphetamine (MDMA) (<0.5-829 ng/mL) and/or methylenedioxyamphetamine (MDA) (10.1 - 460.6 ng/mL), found in 27 samples, and cocaine (13.0-407.3 ng/mL) and its metabolites (benzoylecgonine 0.17-214.1 ng/mL; ecgonine methyl ester 1.8-150.1 ng/mL) in eight samples. Methamphetamine (11-439 ng/mL) was detected in eight samples, along with MDMA and MDA; eutylone was detected in two cases (4.7 and 24.1 ng/mL) reported as "ecstasy" ingestion. A comparison between self-reported drug use and results of oral fluid analysis indicated that the use of illicit substances is often underreported among EDM attendees, who are often unaware of the substances they consume.

Hydrophobic carboxymethyl cellulose as a clean-up sorbent in the determination of nitrofuran metabolites in animal-fat samples

Hydrophobic carboxymethyl cellulose (CMC) biopolymers were fabricated for the removal of fat from food sample matrices. The hydrophobic CMCs were synthesised via the esterification of CMC with three alcohols with carbon chains of different lengths, methanol, butanol, and octadecanol, in the presence of sulfuric acid. The structure of the three synthesised hydrophobic CMCs was verified using FT-IR, and the physicochemical properties were investigated by TGA, SEM, and X-ray. Characterization confirmed the successful synthesis of the hydrophobic CMCs and that the hydrophobic groups are embedded in the sorbent biopolymer to interact with fat and reduce the fat content of the sample extract. Moreover, the performance of the fabricated hydrophobic CMCs was studied in two applications: fat removal and the determination of nitrofuran (NF) metabolites in fat samples. In the first application, excellent results were observed for fat removal; the highest percentage of fat removed from food sample extracts was 94.2% and the lowest was 88.5%. Successful results were also observed in the determination of NF metabolites in fat samples, as the final extract was clear and pure using the hydrophobic CMCs, while it was turbid for the control sample. In addition, the recovery of four NF metabolites was in the range of 97-117%. In general, the hydrophobic CMCs showed promising and satisfactory results, with CMC-C18 exhibiting the best results. The NF detection method was validated using CMC-C18 in three spiking levels; 0.5, 1.0 and 1.5 μg kg-1. The average recoveries of NF range between 83.3 to 104.3%, and the intra-day precision was determined by coefficient of variation, which was below 10% for all NF. The limit of detection and limit of quantification were between 0.6 to 0.9 and 0.20 to 0.28 μg kg-1 respectively. For linearity, the correlation coefficient (r2) was higher than 0.99 for NF metabolites. Overall, the hydrophobic CMCs can be further developed and safely used as green sorbents in food analysis applications.

Electropolymerization of Metallo-Octaethylporphyrins: A Study to Explore Their Sensing Capabilities

The electropolymerization of metallo-octaethylporphyrins (OEP) containing copper, zinc or nickel metal were performed using cyclic voltammetry at three different potential ranges. The electropolymerized porphyrins were characterized by UV-Vis and Raman spectroscopies and the Soret band (393-445 nm) and Raman bands were used to assess the degree of electropolymerization obtained. The application for an analytical use of the modified electrodes to determine phenobarbital in aqueous solution was evaluated. The electropolymerized CuOEP produced at potentials ranging from 0.0 to 2.2 V was the best performer with a limit of detection (LoD) of 10 mg L^-1 (43.07 µM), a linear range of 10-150 mg L^-1 (43.07 to 646 µM), an average precision of 4.3% (%RSD) and an average % recovery of 101.34%. These results indicate that the CuOEP-modified electrode is suitable for the analysis of phenobarbital in human samples, as the concentration range varies from 10 to 40 mg L^-1 (43.07 to 172.27 µM), typically found in antiepileptic treatments, to those at the toxic level (172-258 µM) or lethal levels (345-650 µM).

Development and Validation of a Method for Quantification of 28 Psychotropic Drugs in Postmortem Blood Samples by Modified Micro-QuEChERS and LC-MS-MS

The development of new sample preparation alternatives in analytical toxicology leading to quick, effective, automated and environmentally friendly procedures is growing in importance. One of these alternatives is the QuEChERS, originally developed for the analysis of pesticide residues, producing cleaner extracts than liquid-liquid extraction, and easier separation of aqueous and organic phases. However, there are few published studies on the miniaturization of this technique for forensic toxicology, especially in postmortem analysis. We developed and validated a modified micro-QuEChERS and LC-MS-MS assay to quantify 16 antidepressants, 7 antipsychotics and 3 metabolites and semi-quantify norfluoxetine and norsertraline in postmortem blood. The calibration curve was linear from 1 to 500 ng/mL, achieved an r > 0.99, with all standards quantifying within ±15% of target except ±20% at the limit of quantification of 1 ng/mL for 26 substances. The F test was applied to evaluate if the variance between replicates remained constant for all calibrators. Six weighting factors were analyzed (1/x, 1/x2, 1/x0,5, 1/y, 1/y2 and 1/y0,5), with the weighting factor with the lowest sum of residual regression errors (1/x2) selected. No endogenous or exogenous interferences were observed. Method imprecision and bias were <19.0% and 19.7%, respectively. Advantages of this method include a low sample volume of 100 µL, simple but effective sample preparation and a rapid 8.5-min run time. The validated analytical method was successfully applied to the analysis of 100 authentic postmortem samples.

Technologies to improve the sensitivity of existing chromatographic methods used for bioanalytical studies

Chromatographic method has long been recognized as the most widely used separation method in bioanalytical research. However, the relatively low sensitivity of existing chromatographic methods remains a significant challenge, as the requirements for experimental procedures become more demanding. This review discusses the main causes for the low sensitivity of chromatographic methods and aims to introduce different technologies for enhancing their sensitivity in the following aspects: (i) different pretreatment methods for improving clean-up efficiency and recovery; (ii) derivatization step for altering the chromatographic behavior of analytes and enhancing MS ionization efficiency; (iii) optimal LC-MS conditions and appropriate separation mechanism; and (iv) applications of other chromatographic methods, including miniaturized LC, 2D-LC, 2D-GC, and supercritical fluid chromatography. Altogether, this review is devoted to summarizing the recent technologies reported in the literature and providing new strategies for the detection of bioanalytes.