Extended Stability Evaluation of Selected Cathinones

Automatic MDSPE Combined with DART-HRMS for the Rapid Quantitation of 21 Synthetic Cathinones in Urine

A new, rapid, and automated method for the quantitation of 21 synthetic cathinones in urine was established using magnetic dispersive solid-phase extraction (MDSPE) in combination with direct analysis in real time-high-resolution mass spectrometry (DART-HRMS). Sample preparation and quantitation were verified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methcathinone-D3, α-PVP-D8, and proadifen (SKF525A) were used as internal standards. Magnetic HLB extractant and NaH2PO4/NaOH buffer (0.2 M, pH 7) were used in automatic MDSPE. All 21 synthetic cathinones could be detected and analyzed by DART-HRMS in under 1 min. It was proven that the linearities of 21 synthetic cathinones were suitable (R2 > 0.99) in the concentration ranges of 0.5-100 ng/mL or 1-100 ng/mL. The precision and accuracy values were all within ±15%, and the samples were stable under various conditions. The average time of each sample from preprocessing to completion of detection was approximately 2 min, allowing for rapid sample analysis. The relative error (RE) of the concentrations obtained by DART-HRMS and LC-MS/MS were within ±13.61%, and the linear coefficient (R) was 0.9964. The results of DART-HRMS and LC-MS/MS provided equivalent values at the 95% confidence level. In summary, a simple, fast, and convenient quantitation method via DART-HRMS was established. This application can be utilized to reduce backlogs and promote rapid case processing.

Simultaneous Determination and Stability Analysis of Ten New Psychoactive Substances including Synthetic Cathinones, Phenethylamines, and Ketamine Substitutes in Urine Using Liquid Chromatography-Tandem Mass Spectrometry

Knowing the stability of drugs is important to ensure accurate and reliable results of drug concentrations. This study evaluated the stability of ten new psychoactive substances (NPSs) in urine and methanol/water at different storage temperatures. Quantitative analyses were performed using liquid chromatography-tandem mass spectrometry. Three replicates of each storage condition were analyzed at day 0 and after 7, 14-, 30-, 60-, and 90 days with storage at +25°C, +4°C, and -20°C. For each analyte, the percent difference at each time interval from day 0 was calculated for each storage condition. Para-methoxyamphetamine (PMA), para-methoxymethamphetamine (PMMA), deschloroketamine (DCK), and 2-fluorodeschloroketamine (2-FDCK) were stable in urine, even when stored for 90-day periods at various temperatures. For synthetic cathinones, the concentrations declined over time at room temperature (+25°C) in urine but were relatively stable in methanol solvent with 0.1% formic acid. The significant degradation was found at +25°C, and the most excellent stability was shown by samples stored at -20°C. Phenethylamines (PMA and PMMA) and ketamine substitutes (DCK and 2-FDCK) were relatively more stable than synthetic cathinones (mephedrone, butylone, pentylone, ephylone, 4-MEAPP, and eutylone).

Stability of nonsteroidal anti-inflammatory drugs in urine and solution: effects of degradation on analytical assessment

Aims: Knowledge of optimal storage conditions of drugs is crucial for properly interpreting analytical assessments. Materials & methods: The current study aimed to investigate the stability of some nonsteroidal anti-inflammatory drugs using a validated method by gas chromatography (GC)-MS. For this propose, long-term, short-term and solution stability were investigated. Results: The analytes remained stable in the sample, similar to the working solution. The most affected substance over time in both matrix and working solution was phenylbutazone. The freeze-thaw cycle affected flunixin and carprofen, but diclofenac and vedaprofen changed only in the third cycle. In short-term stability, high-temperature conditions changed carprofen. Conclusion: The present study is a comprehensive assay for nonsteroidal anti-inflammatory drug stability and can be used as a reference for results assessment.

Development and validation of a chiral LC-MS/MS method for the separation and quantification of four synthetic cathinones in human whole blood and its application in stability analysis

Synthetic cathinones, a subclass of new psychoactive substances, have gained high popularity on the recreational drugs market over the past years. These drugs typically have a chiral center, so they may exist as two stereoisomers. Therefore the pharmacological, pharmacokinetic or metabolic properties of their enantiomers are expected to differ. However, these drugs are often synthesized and sold as a racemic mixture, and as a consequence, differentiation of their (R)- and (S)- enantiomers is relevant in clinical and forensic toxicology. Information about single enantiomers of synthetic cathinones is relatively scarce due to challenges of their chiral analysis. Hence, a sensitive and reliable liquid chromatography-tandem mass spectrometry method was developed and validated for the chiral separation and quantification of four synthetic cathinones in human whole blood samples. The method was fully validated in terms of linearity, limit of detection, limit of quantification, bias, precision, carryover, interferences, matrix effects, recovery and processed sample stability and successfully applied to evaluate the stability as well as enantioselective degradation of synthetic cathinones enantiomers under various storage conditions. For most of the analytes, significant enantioselective degradation was observed when stored at room temperature or refrigerated, with the E2-enantiomers observed to more rapidly degrade under both conditions. This is the first report concerning the stability and enantioselective degradation of synthetic cathinone enantiomers in whole blood. Moreover, the inversion study demonstrated enantiomeric inversion of R-(-)- and S-(+)-methylenedioxypyrovalerone (MDPV) in human whole blood and methanolic solution.

Synthesis of emerging cathinones and validation of a SPE GC-MS method for their simultaneous quantification in blood

Over the past 15 years, synthetic cathinones have emerged as an important class of new psychoactive substances (NPS) worldwide. The proliferation of these psychostimulants and their sought-after effects among recreational drug users pose a serious threat to public health and enormous challenges to forensic laboratories. For forensic institutions, it is essential to be one step ahead of covert laboratories, foreseeing the structural changes possible to introduce in the core skeleton of cathinones while maintaining their stimulating activity. In this manner, it is feasible to equip themselves with standards of possible new cathinones and validated analytical methods for their qualitative and quantitative detection. Therefore, the aim of the work herein described was to synthesize emerging cathinones based on the evolving patterns in the illicit drug market, and to develop an analytical method for their accurate determination in forensic situations. Five so far unreported cathinones [4'-methyl-N-dimethylbuphedrone (4-MDMB), 4'-methyl-N-ethylbuphedrone (4-MNEB), 4'-methyl-N-dimethylpentedrone (4-MDMP), 4'-methyl-N-dimethylhexedrone (4-MDMH), and 4'-methyl-N-diethylbuphedrone (4-MDEB)] and a sixth one, 4'-methyl-N-ethylpentedrone, already reported to EMCDDA and also known as 4-MEAP, were synthesized and fully characterized by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). An analytical method for the simultaneous quantification of these cathinones in blood, using solid phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) was developed and validated. The results prove that this methodology is selective, linear, precise, and accurate. For all target cathinones, the extraction efficiency was higher than 73%, linearity was observed in the range of 10 (lower limit of quantification, LLOQ) to 800 ng/mL, with coefficients of determination higher than 0.99, and the limits of detection (LODs) were 5 ng/mL for all target cathinones. The stability of these cathinones in blood matrices is dependent on the storage conditions; 4-MNEB is the most stable compound and 4-MDMH is the least stable compound. The low limits obtained allow the detection of the compounds in situations where they are involved, even if present at low concentrations.

Utilization of Machine Learning for the Differentiation of Positional NPS Isomers with Direct Analysis in Real Time Mass Spectrometry

The differentiation of positional isomers is a well established analytical challenge for forensic laboratories. As more novel psychoactive substances (NPSs) are introduced to the illicit drug market, robust yet efficient methods of isomer identification are needed. Although current literature suggests that Direct Analysis in Real Time–Time-of-Flight mass spectrometry (DART-ToF) with in-source collision induced dissociation (is-CID) can be used to differentiate positional isomers, it is currently unclear whether this capability extends to positional isomers whose only structural difference is the precise location of a single substitution on an aromatic ring. The aim of this work was to determine whether chemometric analysis of DART-ToF data could offer forensic laboratories an alternative rapid and robust method of differentiating NPS positional ring isomers. To test the feasibility of this technique, three positional isomer sets (fluoroamphetamine, fluoromethamphetamine, and methylmethcathinone) were analyzed. Using a linear rail for consistent sample introduction, the three isomers of each type were analyzed 96 times over an eight-week timespan. The classification methods investigated included a univariate approach, the Welch t test at each included ion; a multivariate approach, linear discriminant analysis; and a machine learning approach, the Random Forest classifier. For each method, multiple validation techniques were used including restricting the classifier to data that was only generated on one day. Of these classification methods, the Random Forest algorithm was ultimately the most accurate and robust, consistently achieving out-of-bag error rates below 5%. At an inconclusive rate of approximately 5%, a success rate of 100% was obtained for isomer identification when applied to a randomly selected test set. The model was further tested with data acquired as a part of a different batch. The highest classification success rate was 93.9%, and error rates under 5% were consistently achieved.

Prevalence of cathinones and other new psychoactive substances in hair of parents and children of families with known or suspected parental abuse of conventional illegal drugs

BACKGROUND

Hair analysis of parents and their children was regularly used since 2011 as a diagnostic tool in a social support project for families with known or suspected abuse of conventional illegal drugs and revealed a high incidence of cocaine, cannabinoids, amphetamines, ecstasy and heroin. In this context, the prevalence of new psychoactive substances (NPS) in these families should be important for a realistic estimate of the situation.

METHODS

The extracts of 1537 hair samples from 318 children (age 1-14 years), 44 adolescents and 611 adults, which were collected and tested for conventional drugs between June 2016 and April 2021 and frozen at -20 °C, were reanalyzed by a validated LC-MS/MS method (limits of quantitation 5-24 pg/mg) for 33 cathinones, 10 phenylethylamines, 5 piperazines including the antidepressant trazodone, 2 tryptamines, 9 designer benzodiazepines, 4 synthetic opioids and 4 ketamine-like substances including phencyclidine.

RESULTS

Between one and up to five from 42 of these substances were detected in 227 samples (14.8%). The most frequently detected substances were benzedrone (62x), α-pyrrolidinovalerophenone (41x), N-ethylamphetamine (29x), dimethyltryptamine (13x) and pyrovalerone (11x). The quantification was possible only for 34 results of 15 drugs and the remaining majority of the results were unambiguously identified below LLOQ. The relative frequency of conventional drugs in the 227 NPS positive samples was higher than in all 1310 NPS negative samples for cocaine (69.6% vs. 56.0%), heroin (6-acetylmorphine 8.8% vs. 4.9%), amphetamine (16.3% vs. 7.7%) and MDMA (16.3% vs. 7.0%) but was similar for THC (38.3% vs. 36.3%) and benzodiazepines (1.8% vs. 1.7%). The high prevalence of N-ethylamphetamine can be explained as a byproduct of the illicit amphetamine synthesis from benzaldehyde and nitroethane rather than as a separate drug or as a combined metabolite of amphetamine and ethanol. The isolated appearance of 3-trifluoromethylphenylpiperazine in 9 hair samples collected in January 2017 can be caused either by its use as an NPS or by its formation as a metabolite of the medical drug flibanserin. The results were compared within 17 families whose members were tested at the same time and showed positive NPS results. The detected drugs agreed between both parents only in about half of the cases whereas the drugs found in children's hair was always detected also in hair of one or both parents.

CONCLUSION

The re-testing of hair extracts for NPS after long-time storage in frozen state enables an impression about the relative high prevalence in the tested population group, despite the limitation by partial degradation of the substances and the corresponding impossibility in quantitative assessments. In addition to conventional drugs, the hair test for these substances should be useful in unclear cases of child's welfare endangerment and in family law.

Rapid quantitation of three synthetic cathinones in urine by magnetic dispersive solid-phase extraction combined with DART-HRMS

For the rapid quantitation of three synthetic cathinones, namely 1-(4-chlorophenyl)-2-(1-pyrrolidinyl)pentan-1-one (4-Cl-α-PVP), 1-(4-methylphenyl)-2-(methylamino)pentan-1-one (4-MPD), and 1-(5,6,7,8-tetrahydronaphthalen-2-yl)-2-(1-pyrrolidinyl)pentan-1-one (β-TH-naphyrone), in urine, a new method was established using magnetic dispersive solid-phase extraction (MDSPE) combined with direct analysis in real time and high-resolution mass spectrometry (DART-HRMS). Methcathinone-D3 and proadifen (SKF525A) were used as the internal standards. Hydrophobic magnetic adsorbents were used and consisted of hydrophobic functional group (divinylbenzene) and hydrophilic functional group (vinylpyrrolidone) at a ratio of 3 : 1, and NaH₂PO₄//NaOH buffer (0.2 M, pH 7) was used in MDSPE. Detection was conducted by DART-HRMS in less than 1 min. For 4-Cl-α-PVP, 4-MPD and β-TH-Naphyrone, the limits of detection were 0.1 ng mL^-1, 0.05 ng mL^-1 and 0.1 ng mL^-1, and the linear ranges were 0.5-100 ng mL^-1, 0.2-100 ng mL^-1 and 0.2-100 ng mL^-1, respectively. The correlation coefficients were all greater than 0.99. The precision and deviation of accuracy were all within ±15%, and the stability of the samples was high under various conditions. The method was successfully applied to detect 4-Cl-α-PVP, 4-MPD and β-TH-naphyrone in rat urine after subcutaneous administration. In summary, a fast and convenient detection method was established, providing new and effective technical support for the rapid quantitation of three synthetic cathinones (4-Cl-α-PVP, 4-MPD and β-TH-Naphyrone) for forensic purposes.

Sensitive Screening of New Psychoactive Substances in Serum Using Liquid-Chromatography Quadrupole Time-of-Flight Mass Spectrometry

Analysis of new psychoactive substances (NPS) still pose a challenge for many institutions due to the number of available substances and the constantly changing drug market. Both new and well-known substances keep appearing and disappearing on the market, making it hard to adapt analytical methods in a timely manner. In this study we developed a qualitative screening approach for serum samples by means of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Samples were measured in data-dependent auto-MS/MS mode and identified by fragment spectra comparison, retention time and accurate mass. Approximately 500 NPS, including 195 synthetic cannabinoids, 180 stimulants, 86 hallucinogens, 26 benzodiazepines and 7 others were investigated. Serum samples were fortified to 1 ng/mL and 10 ng/mL concentrations to estimate approximate limits of identification. Samples were extracted using solid-phase extraction with non-endcapped C18 material and elution in two consecutive steps. Benzodiazepines were eluted in the first step, while substances of other NPS subclasses were distributed among both extracts. To determine limits of identification, both extracts were combined. 96 % (470/492) of investigated NPS were detected in 10 ng/mL samples and 88 % (432/492) were detected in 1 ng/mL samples. Stimulants stood out with higher limits of identification, possibly due to instability of certain methcathinone derivatives. However, considering relevant blood concentrations, the method provided sufficient sensitivity for stimulants as well as other NPS subclasses. Data-dependent acquisition was proven to provide high sensitivity and reliability when combined with an information-dependent preferred list, without losing its untargeted operation principle. Summarizing, the developed method fulfilled its purpose as a sensitive untargeted screening for serum samples and allows uncomplicated expansion of the spectral library to include thousands of targets.