The identification of isomeric drugs is gaining increasing importance in forensics and doping control. Isomers vary in terms of safety, effectiveness, and regulation, particularly for amphetamine-related drugs (ARDs). This study developed and validated a pseudo-isocratic UPLC-qTOF-MS analytical method for the identification of isomeric Amphetamine-related drugs (ARDs) in blood following mixed-mode solid-phase extraction (MMSPE). The procedure requires 250 μL of blood to achieve a limit of quantification (LOQ) and detection (LOD) of 20 ng/mL for all analytes. In aged animal blood samples, extraction recoveries of 63–90% and matrix effects of 9–21% were observed. Precision and accuracy for all analytes were within 20% and 89–118%, respectively. The analytical method was developed and validated in accordance with the Scientific Working Group for Forensic Toxicology (SWGTOX) Standard. It has acceptable accuracy and precision for use in doping control and forensic toxicology.

Abuse of amphetamine-related drugs (ARDs) causes traffic accidents, violence, and overdose. In forensic toxicology, analysis for ARDs in biological samples can help identify those driving or performing other tasks under the influence of drugs, clarify the cause of death, and identify recent drug users. In this study, we validated a pseudo-isocratic UPLC-qTOF-MS method following mixed mode cation exchange (MMSPE) extraction for analysis of ARDs in blood. The procedure requires 250 μL of blood to achieve a limit of quantification (LOQ) and detection (LOD) of 20 ng/mL for all analytes. In aged animal blood samples, extraction recoveries of 63-90% and matrix effects of 9-21% were observed. Precision and accuracy for all analytes were within 20% and 89–118%, respectively. The analytical method was developed and validated in accordance with the Scientific Working Group for Forensic Toxicology (SWGTOX) Standard. It has acceptable accuracy and precision for use in doping control and forensic toxicology.

Cathinone is a natural stimulant found in Catha edulis and commonly used in new psychoactive substances. The objective of this study was to examine the disposition kinetics and metabolic profile of cathinone and its metabolite cathine through a single oral dose of cathinone administration in rats. Cathine and cathinone concentrations were identified and quantified using ion trap liquid chromatography (LC-IT/MS), while the metabolic profile was determined using the quadrupole time of flight UPLC-QTOF/MS method in the serum, brain, lung, liver, kidney, and heart over a period of 0, 0.5, 2.5, 6, 12, 24, 48, and 72 hours. The findings revealed a dynamic interplay between the pharmacokinetics of cathinone and its impact on organ-specific biomarkers. The distribution of cathinone and cathine was determined in serum, brain, heart, lung, kidney, and liver. The highest concentration of cathinone was found in the kidney at 1438.6 ug/L. It gradually decreased to 1.97 within 48 hours and disappeared after 72 hours. Within half an hour, cathinone levels in the lungs, liver, and heart were found to be 859, 798.9, and 385.8 ug/L, respectively. However, within 2.5 hours, these levels decreased to 608.1, 429.3, and 309.1 ug/L and kept decreasing until they became undetectable after 24 hours. The concentration of cathinone in the rat brain reduces quickly, dropping to undetectable levels within six hours, with levels decreasing from 712.7 ug/L after just 30 minutes. In the brain and serum, cathine reached its highest levels at 2.5 hours, while in other organs, it peaked at 0.5 hours. This indicates that the conversion of cathinone to cathine is slower in the brain and serum. The study found that cathinone's pharmacokinetics have a significant impact on organ-specific biomarkers. After administering the cathinone, there was a sharp change in biomarker levels, particularly in the liver and brain, during the initial hours. It is essential to investigate the correlation between the changes in biomarkers found in the brain and the levels of cathinone and cathine. The results have significant implications for drug development, pharmacovigilance, and clinical practices involving cathinone. In conclusion, this comprehensive analysis of cathinone's impact on organ-specific biomarkers provides a basis for informed decision-making in medical practices and further research into the cathinone's pharmacological properties.

β-Methylphenethylamine (BMPEA), a positional isomer of amphetamine increasingly detected in dietary supplements and weight-loss products, poses significant analytical challenges in forensic and doping control due to its structural similarity to amphetamine. This study presents a validated analytical workflow combining mixed-mode solid-phase extraction (MMSPE) with ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC-qTOF-MS) for the selective quantification of BMPEA and identification of its metabolites in rat cardiac blood. Blood was taken at 20 and 90 min after injection from twelve adult male Sprague-Dawley rats that were randomly assigned to four groups (n = 3): an untreated control, a low-dose cohort (10 mg/kg, i.p.), and two high-dose cohorts (30 mg/kg, i.p.). The technique demonstrated strong differentiation between BMPEA and amphetamine isomers, excellent linearity over 20–1000 ng/mL (R² > 0.99), and quantification limits appropriate for forensic applications. A short biological half-life and quick elimination kinetics are consistent with related phenethylamines, as evidenced by the peak BMPEA concentrations of 899 ng/mL at 20 min and 22 ng/mL at 90 min. Comprehensive low- and high-energy mass spectrometric analyses revealed a novel BMPEA metabolite, characterized as 1-amino-2-phenylpropan-2-ol, based on fragmentation patterns and retention time comparison with reference standards. This work delivers a rigorous, high-sensitivity analytical tool for BMPEA detection in biological matrices and enhances understanding of its metabolic fate, offering critical biomarkers for forensic toxicology and anti-doping investigations.

β-Methylphenethylamine (BMPEA), a positional isomer of amphetamine increasingly detected in dietary supplements and weight‐loss products, poses significant analytical challenges in forensic and doping control due to its structural similarity to amphetamine. This study presents a validated analytical workflow combining mixed‐mode solid‐phase extraction (MMSPE) with ultra‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry (UPLC-qTOF-MS) for the selective quantification of BMPEA and identification of its metabolites in rat cardiac blood. Blood was taken at 20 and 90 minutes after injection from twelve adult male Sprague-Dawley rats that were randomly assigned to four groups (n = 3): an untreated control, a low-dose cohort (10 mg/kg, i.p.), and two high-dose cohorts (30 mg/kg, i.p.). The technique demonstrated strong differentiation between BMPEA and amphetamine isomers, excellent linearity over 20–1,000 ng/mL (R2 > 0.99), and quantification limits appropriate for forensic applications. A short biological half-life and quick elimination kinetics are consistent with related phenethylamines, as evidenced by the peak BMPEA concentrations of 899 ng/mL at 20 min and 22 ng/mL at 90 min. Comprehensive low- and high-energy mass spectrometric analyses revealed a novel BMPEA metabolite, characterized as 1-amino-2-phenylpropan-2-ol, based on fragmentation patterns and retention time comparison with reference standards. This work delivers a rigorous, high‐sensitivity analytical tool for BMPEA detection in biological matrices and enhances understanding of its metabolic fate, offering critical biomarkers for forensic toxicology and anti-doping investigations.