Illegal adulteration of herbal weight-loss supplements with sibutramine (SIB) and its structurally related analogues remains a significant public health concern, highlighting the need for reliable, accessible, and cost-effective analytical methods for routine regulatory surveillance. In this study, a high-performance liquid chromatography method coupled with photodiode-array detection was developed, chemometrically optimized using Box-Behnken response surface methodology, and validated for the simultaneous determination of SIB, desmethylsibutramine (DMS), and didesmethylsibutramine (DDMS). The effects of mobile-phase pH, flow rate, and column temperature on chromatographic resolution were systematically evaluated to establish optimum separation conditions. Under the optimized conditions, comprising an InertSustain C18 column with gradient elution using acetonitrile and phosphate buffer (pH 3.9), a flow rate of 1.0 mL min[-1], a column temperature of 42.5 °C, and UV detection at 223 nm, complete baseline separation of the three analytes was achieved with chromatographic resolutions of 2.269 (DDMS/DMS) and 4.865 (DMS/SIB). The optimized chromatographic system satisfied all system suitability criteria, exhibiting retention-time RSDs below 0.05%, peak-area RSDs below 1.0%, theoretical plate numbers exceeding 37 000, and tailing factors below 1.45. The method was validated in accordance with ICH Q2(R2) and AOAC guidelines, demonstrating satisfactory linearity (R [2] > 0.99), precision, accuracy, and adequate sensitivity for routine analysis. Application of the validated method to commercial herbal weight-loss supplements successfully identified products adulterated with sibutramine and desmethylsibutramine, and all positive findings were independently confirmed by high-resolution mass spectrometry. The proposed analytical workflow provides a robust, chemometrically optimized, and experimentally validated strategy for the routine regulatory screening and quality control of illegal pharmaceutical adulterants in herbal weight-loss supplements.

Objectives: This study aimed to determine whether eccentric gaze produces a regional, gaze-aligned redistribution of tear-film quality that is more apparent in spatial analysis than in whole-map summary measures. Methods: This was a secondary analysis of a previously acquired Medmont Meridia composite-topography dataset from 38 healthy participants, using only the Medmont data. Tear-film quality maps from the ahead, right, left, up, and down gaze were interpolated onto a common grid, aligned to a shared reference frame, and analysed using descriptive global measures, regional spatial mapping, and a threshold-based directional sector analysis. The threshold analysis used an operational cut-off of 0.35 to classify good-quality pixels, with lower values indicating better tear-film quality. Robustness was assessed by repeating the same analysis across nearby cut-offs from 0.30 to 0.40. As Placido-based topography measures reflection from the tear layer rather than the ocular surface itself, and as ocular rotation changes lid position and exposed ocular surface area, aligned comparisons were interpreted as comparisons of the exposed tear-film pattern rather than exact point-for-point anatomical tracking. Results: Global tear-film summary measures showed only modest variation with gaze direction, whereas spatial mapping revealed systematic regional redistribution of tear-film quality across eccentric gaze conditions. At the 0.35 operational threshold, the gaze-aligned good-pixel index was positive for right gaze (0.297 ± 0.200), left gaze (0.213 ± 0.174), up gaze (0.204 ± 0.219), and down gaze (0.308 ± 0.260). All four indices remained greater than zero after Holm correction (all pHolm < 0.001), and all remained greater than the matched ahead-gaze sector indices (all pHolm < 0.001). Threshold sensitivity analysis across cut-offs from 0.30 to 0.40 showed that the positive directional pattern was preserved for all gaze directions. Conclusions: Tear-film quality varies regionally with gaze direction, a pattern that was clearer in spatial maps and sector indices than in global summaries. Straight-ahead measurements may therefore provide an incomplete account of tear-film behaviour during eccentric gaze. As the analysis involved healthy participants and did not assess symptoms or diagnostic performance, the clinical relevance of this pattern requires validation in symptomatic populations.

Sports nutrition supplements occupy an unstable boundary between food, performance culture, pharmaceutical exposure, and environmental contaminant control. Their matrices include protein powders, creatine products, stimulant pre-workouts, slimming capsules, plant extracts, tablets, functional beverages, and sexual-enhancement products marketed to physically active consumers. This review synthesizes trends in microchemical detection of illegal adulterants and heavy metals in these products, with emphasis on low-sample and low-solvent preparation, rapid screening, confirmatory mass spectrometry, elemental analysis, and multi-contaminant risk interpretation. The evidence base includes athlete supplement-use reviews, market-surveillance studies, targeted and non-target LC-MS/HRMS methods, Raman/SERS and paper-based sensors, ICP-MS/ICP-OES/XRF metal studies, and quantitative risk-assessment papers. Anabolic agents, stimulants, sibutramine, sildenafil analogues, SARMs, prohormones, diuretics, beta2-agonists, glucocorticoids, and 2,4-dinitrophenol are considered together with Pb, Cd, As, Hg, Cr, Ni, Cu, Zn, and other elements. Across the literature, the main trend is not replacement of laboratory confirmation by portable tools, but redistribution of analytical work: field screening, microextraction, and chemometric triage reduce sample and solvent burdens, while LC-MS/MS, HRMS, and ICP-based methods remain decisive for quantification, legal defensibility, and retrospective identification. Regulatory value increases when adulterant and metal data are interpreted jointly because the same product may carry anti-doping risk, acute pharmacological risk, and chronic elemental exposure.

Rapid detection techniques play a critical role in the field of food hazard factor analysis, as food safety constitutes a fundamental cornerstone of public health. However, the application of Surface-Enhanced Raman Scattering (SERS)-lateral flow immunoassay (LFIA) as a rapid detection method in this area still faces significant challenges. Consequently, traditional quantification methods that rely on average Raman signal intensity often prove inadequate for accurate measurement under such conditions. In response to these limitations, we developed a digital SERS-LFIA approach, which employs digital analytical techniques to process Raman spectral data for the ultrasensitive and quantitative analysis of sibutramine (SIB), a central appetite suppressant formerly used in obesity treatment that is now frequently illicitly added to foods such as weight-loss teas. Specifically, the method utilized core-shell Ag-coated Au nanoparticles functionalized with Raman reporter molecules as SERS tags. SERS-LFIA strips were prepared via antigen-antibody recognition for SIB detection. Rapid Raman mapping of the T-line region generated spatially resolved signal matrices, which were converted to binary values 0/1 by applying an intensity threshold at the reporter's characteristic peak. Quantification was accomplished by correlating the positive signal frequency with SIB concentration, effectively mitigating the interference caused by signal heterogeneity and background signals on quantification. Compared with conventional Raman average intensity analysis, the digital SERS-LFIA achieved limits of detection of 0.28 ng/mL, demonstrating excellent quantitative detection capability. In summary, by incorporating digital SERS technology, this study extends the application of LFIA to enable ultrasensitive and efficient quantitative detection analytes in complex food samples.

Current society is facing the global surge in obesity rates, making people more aware of the importance of body weight control and increasing the consumption of weight-loss supplements due to their over-the-counter status. However, certain producers have intentionally adulterated supplements with prescription weight-loss drugs without label declaration, necessitating suitable analytical methods for routine analysis of illegal weight-loss compounds in health supplements. In this study, a rapid, effective, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of 11 wt-loss compounds in three supplement forms (i.e., hard capsule, soft capsule, and tea powder). A suitable analytical procedure was selected via the optimization of LC-MS/MS parameters and sample preparation conditions. The samples were ultrasonicated with methanol, and the extracts were cleaned up using dispersive solid-phase extraction with C18 and carbon sorbent. The method was validated for specificity, linearity, method detection and quantification limits, precision, and accuracy, producing good satisfaction. The method was applied to analyze 82 health supplement samples collected from the Vietnamese market, in which seven samples were found to be adulterated with at least one of the target compounds. Sibutramine, phenolphthalein, and benzylsibutramine were detected in 7/82, 5/82, and 2/82 samples with concentration ranges of 0.44-16.4, 0.54-2.14, and 0.14-1.43 mg/g, respectively. These results indicated the method applicability to the quality control of health supplements in developed and emerging countries.

A lab-made robotic system is presented that integrates an arc discharge air plasma generator with automated X- and Y-axis motion, enabling rapid treatment (25 s per 0.19 cm[2]) of graphite sheet (GS) electrodes with improved reproducibility compared to manual handheld plasma treatment. Scanning electron microscopy (SEM) revealed an increase in surface roughness and the formation of 3D nanoflake structures following plasma treatment. Complementary Raman spectroscopy analysis showed an elevated D-to-G band intensity ratio (ID/IG), indicating a higher density of structural defects. Electrochemical characterization using cyclic voltammetry demonstrated enhanced electrochemical responses for ferricyanide and various organic compounds, including catechol, codeine, ketamine, paracetamol, sibutramine, and uric acid. The improvements were observed as increased current intensities and negative shifts in redox peak potentials, reflecting enhanced electron transfer kinetics at the treated electrode surface. The lower charge transfer resistance measured by electron impedance spectroscopy (EIS) and the higher heterogeneous electron transfer rate constant (k0) obtained for plasma-treated GS electrodes are consistent with these results. As proof of concept, treated GS sensors were used to detect uric acid, an important clinical biomarker, in spiked synthetic saliva and urine samples, using optimized differential pulse voltammetry (DPV) conditions. Linear ranges (between 1.0 and 400.0 and 400.0–1000.0 µmol L− 1) and a limit of detection (LOD) of 0.08 µmol L− 1 were achieved. Appropriate recovery values (106–109%) were also obtained for the analysis of spiked samples.

Obesity, defined as excessive fat accumulation that impairs health, is a global challenge with high mortality rates. Sibutramine, a centrally acting anorectic, was widely used in obesity treatment due to its effects on appetite control and weight loss. It represented a key step in anti-obesity pharmacotherapy before being withdrawn in many countries. This study evaluates how a high sibutramine dose (10 mg.kg.day-1 followed by 13 mg.kg.day-1) influences body weight, biochemical profiles, liver and intestinal health, and gut microbiota composition in rats subjected to a cafeteria diet for 16 weeks. Rats treated with sibutramine exhibited a 10.93% reduction in body weight and improved glycemic control compared to untreated groups. Sibutramine modulated lipid profiles by lowering total cholesterol and increasing HDL levels in controlled diet groups. The treatment attenuated liver damage markers (AST and ALT) and increased intestinal crypt depth, suggesting gut integrity. The elevated sibutramine dose led to distinct microbiota shifts, partially reversing cafeteria diet-induced dysbiosis by increasing SCFA-producing genera, including Bacillus, Marvinbryantia, and Bifidobacterium. However, dietary factors remained the dominant driver of microbial composition. These findings underscore the impact of sibutramine's dosing on gut microbiota and reinforce its role in obesity-related health improvements.