ANALYTICAL METHODS FOR METHANOL DETECTION IN ALCOHOLIC BEVERAGES: A COMPARATIVE REVIEW OF CLASSICAL, COLORIMETRIC, AND CHROMATOGRAPHIC APPROACHES
Introduction: The detection of methanol in alcoholic beverages represents a critical public health issue, particularly in light of the recent outbreak of poisonings in Brazil, which registered 58 confirmed cases and 15 deaths through October 2025. Methanol's toxicity, with an estimated lethal dose ranging from 0.5 to 1.5 g/kg, requires reliable analytical methods for health surveillance. Brazilian legislation establishes a maximum limit of 20 mg/100 mL of anhydrous alcohol; however, the need for accessible screening methods in field settings remains an important challenge. Objective: To critically compare three analytical methods for methanol determination: classical qualitative methods (Lucas Test and dichromate/Schiff), Brazilian colorimetric method, and gas chromatography with flame ionization detector (GC-FID), evaluating their performance and applicability in resource-limited contexts. Methods: Theoretical-comparative approach through critical analysis of specialized literature and normative technical documentation. Methods were evaluated according to: operational principle, sensitivity (LOD/LOQ), selectivity, operational complexity, analysis time, and practical applicability. Results: The Lucas Test is not applicable for methanol detection. Colorimetric methods showed moderate sensitivity (LOD ~20-160 mg/100 mL), a 10-30-minute execution time, low operational complexity, and excellent portability. The Brazilian method presented chemical equivalence with international standards, differing only in the type of reading performed. GC-FID has shown superior sensitivity (LOD ≤ 1 mg/100 mL) and high specificity, but it requires extended time (~45-60 minutes), complex laboratory infrastructure, and specialized operators. Sugars interfere with colorimetric methods. Conclusions: The methods are complementary within a hierarchical system. Colorimetric methods enable rapid field screening, while GC-FID serves as the confirmatory method for forensic analyses. We recommend implementing integrated protocols that combine in situ colorimetric screening with GC-FID confirmation in accredited laboratories for effective health surveillance.
Read ArticleSELF-ASSEMBLED MULTILAYERS OF WATER GLUCOSE MODIFIED-CHITOSAN AND GLUCOSE OXIDASE FOR DETECTION OF GLUCOSE IN MILK SAMPLES
Background: A crucial aspect of electrochemical enzymatic biosensor development is the immobilization of the enzymes, as it directly influences the sensitivity of the bioelectrode. Among the different methods used to incorporate enzymes on the surface of the transducers, layer-by-layer (LbL) self-assembly based on electrostatic interaction with polyelectrolytes of opposite charge stands out due to its simplicity and reproducibility. Aims: The aim of the work was to develop an electrochemical glucose biosensor by LbL assembly of a new functionalized chitosan polycation and the enzyme glucose oxidase (GOx). Methods: Chitosan was chemically functionalized with glucose by the Maillard reaction. The resulting polycation, named G-Chit, is soluble in the medium compatible with the enzyme. The bioelectrode was obtained by alternating adsorption of G-Chit and GOx onto carbon paste electrodes. By selecting the number of bilayer of G-Chit/GOX, the enzyme concentration, and the pH, the electroanalytical performance of the biosensor was optimized. The electrochemical responses were characterized by cyclic voltammetry and chronoamperometry. Results: Under optimized experimental conditions, the biosensor exhibited a sensitivity of (0.81 ± 0.03) µA mM-1 in a glucose concentration range of (0.18 to 1.75) mM. Discussion: Results indicated that catalytic response increases both with the number of G-Chit/GOx bilayers and the enzyme concentration, obtaining the best responses for 3 bilayers and 2 mg mL-1, respectively, while the optimum working pH value was 7.0. Conclusions: The analytical response of the biosensor was tested in milk samples with negligible matrix effects, suggesting a potential application in other dairy products. Results show that G-Chit appears promising for the immobilization of enzymes.
Read ArticleTYPE 2 DIABETES MELLITUS EFFECTS ON SEMEN PARAMETERS AND SEMINAL PLASMA
Background: Diabetes Type 2 is a complex disorder described by an imbalance between insulin resistance and secretion that induce liver glucose output. It has been shown that serum insulin levels are affected by a sperm plasma membrane and acrosome. Therefore, during insulin resistance spermatogenesis changes, diabetic patients detect testicular changes. Aims: This research aims to know the effect of diabetic type 2 on some aspects of fertility in men by studying the characteristics of the semen and some biochemical parameters in seminal plasma. Methods: This study was achieved at the Center for Endocrinology and Diabetes Specialists in Maysan province from February to November 2018 and included 45 men (30 diabetic and 15 healthy in the control group) aged 30 to 59 years. The patients were divided according to age into two groups, the first (30-39) and second (40-59) years, also divided by the duration of diabetes into two groups, the first (1-5) and second (6-10) year. Results: The pH of semen in the second age group (40-49 years) group and first duration (1-5 years) group were significantly decreased (P <0.05) in diabetes compared with the control group. Volume and viscosity did not have significant differences in patients compared to the control following the age and duration of diabetes. Liquefaction only in the first age (30-39 years) group significantly increased (P <0.05) compared to the control. The concentration of sperm, progressive motility, non-progressive and normal morphology decreased (P <0.05) significantly. While the sluggish, dead, and abnormal morphology significantly increased (P <0.05) in all diabetes groups compared with the control. The fructose and alkaline phosphatase values in the seminal plasma were not differing significantly in patients compared with the control. Zinc and glutathione values decreased significantly (P <0.05) compared with control in each age and duration of diabetes. Discussion: Insulin stimulates the Ledying cell function, defect insulin effect on spermatogenesis. Impaired sperm motility in a patient with D.M. might be attributed to many reasons, such as increased ROS level, altered mitochondria DNA, and decreased epididymal products. Conclusion: our measurement indicates that there is an effect of type 2 diabetes mellitus on semen parameters and seminal plasma biochemical parameters.
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