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Background. Beer, red and white wine are acidic drinks whose frequent consumption can increase the risk of dental erosion. Objectives. To establish the effect of beer, red and white wine on the morphology and surface roughness (SR) of human enamel using different exposure times in a cyclic de- and remineralization model in vitro. Materials and methods. The experiment included 33 surgically extracted impacted human third molars from patients aged 18-25 years. Enamel samples obtained by cutting crowns (n = 132) were submitted to alternate cycles of demineralization in (1) beer, (2) red wine, (3) white wine, (PC) positive control (orange juice), and remineralization in artificial saliva, which also represented a medium for negative control (NC). The experiment included cycles with different exposure times in alcoholic beverages and orange juice of 15, 30 and 60 min. Thus, 12 groups were formed (for each drink and each exposure time) containing 10 samples each, while the NC group consisted of 12 samples. Experiments were repeated 3x/day for 10 days. Enamel surface alterations were determined by stylus profilometry (average surface roughness (Ra)) and scanning electron microscopy (SEM). The Shapiro-Wilk test, independent samples Kruskal-Wallis test and multiple comparisons (all pairwise) were performed. Results. With increasing exposure time, there was a positive correlation with Ra for white wine- and orange juice-immersed samples (60 min compared to 15 min), which was also observed using SEM. There was no significant difference in the Ra between the other experimental samples for the same exposure time. Conclusions. This study confirms a certain erosive potential of beer, red and white wine, and a significant relationship with pH, titratable acidity (TA) and SR, but not with the exposure time for all tested alcoholic beverages. Moreover, differences among the ultrastructural patterns caused by alcoholic beverages over the enamel surface were observed. [ABSTRACT FROM AUTHOR]

A simple HPLC method was developed for the determination of antiplatelet drug ticagrelor (TCG) in blood. Sample preparation and extraction conditions were investigated and optimized. The preparation of blood plasma was investigated by protein precipitation using perchloric acid, methanol, acetonitrile (ACN), and trifluoroacetic acid. Protein precipitation using ACN was found to be the most suitable. Chromatographic separation of TCG was performed on a C18 column with a mobile phase consisting of ACN and 15 mM ammonium acetate buffered at pH 8.0. The method was applied to determine TCG in blood plasma of patients who had a heart attack. Blood samples were collected 1.5 h after the administration of the initial loading dose of the antiplatelet drug. The average concentration of TCG was found to be 0.97 ± 0.53 μg/ml. The developed method proved to be very selective, without interferences from other endogenous substances and the influences of possible coadministered drugs. The limits of detection and quantification estimated by the signal‐to‐noise ratio in real samples were 0.24 and 0.4 μg/ml, respectively. The developed method is simple and can be easily applied in clinics and emergency cardiac situations after the initial loading dose of TCG in the first few hours of a heart attack. [ABSTRACT FROM AUTHOR]

The present paper reports determination of α-tocopherol in commercial cow, raw cow and goat milk, as well as estimation of its nutritive value based on α-tocopherol content. Quantification was done by reversed-phase HPLC with fluorescence detection (ex 295 nm, em 330 nm) and with UV detector set at 286 nm and 292 nm. The method of milk sample preparation consisted of alkaline saponification with 30% KOH, denaturation of lipoproteins with methanol followed by liquid-liquid extraction with diethyl-ether. Recovery values of the extraction method were 78.5, 86.7 and 91.0% for three standard addition levels. Analyzed commercial low-fat milk samples had significant lower α-tocopherol levels than milk with higher fat content. α-tocopherol concentration below 0.30 μg/ml in low-fat cow milk and 0.83-0.86 μg/ml in whole milk were detected. Raw goat milk had much more α-tocopherol (1.25 μg/ml) compared with commercial and raw cow milk with similar fat content.

The reaction between NaAsO2 and oxalic acid was studied by pH-metric and conductometric measurements, applying the methods of continual variation and pH-metric and conductometric titration. It was found that oxalic acid forms a complex anion of the type [AsOC2O4]-. The relative stability constant of the complex at ionic strengths, I, of 0.10 (log Kr = 4.70), 0.20 (log Kr=4.51), 0.50 (log Kr = 4.24) and 0 (log K 0 = 5.05) and thermodynamic parameters were calculated using the data obtained by pH-metric measurements at 25.0±0.1°C (DH = 10.5 kJ mol-1, DG = -29.0 kJ mol-1, DS = 133 J mol-1 K-1).

Caffeine is extensively used in cellulite and hair growth cosmetic products. Regulations in the field of cosmetics require manufacturers to list caffeine in the ingredient list on product labels, but its exact content in these products is not declared. On the other hand, daily exposure to caffeine from all sources may approach health reference values. For that reason, it is important to know the exact caffeine content in products for skin and hair care. Cosmetics are often viscous or semisolid products of very complex chemical composition. To analyze caffeine in these complex sample matrices by liquid chromatographic methods, an extraction step is often necessary. This article presents the applicability of the solid-phase extraction (SPE) procedure for the caffeine extraction and high-performance liquid chromatography (HPLC) determination in anticellulite gels, shampoos, and hair balsam. The samples of gels were centrifuged after ammonia addition to precipitate carbomer. In cellulite reduction, gel caffeine content was found to be in the range of 0.7-1.7%, whereas in the hair-care products, it was about 1.0%. [ABSTRACT FROM AUTHOR]

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The reaction between NaAsO2 and oxalic acid was studied by pH-metric and conductometric measurements, applying the methods of continual variation and pH-metric and conductometric titration. It was found that oxalic acid forms a complex anion of the type [AsOC2O4]-. The relative stability constant of the complex at ionic strengths, I, of 0.10 (log Kr = 4.70), 0.20 (log Kr = = 4.51), 0.50 (log Kr = 4.24) and 0 (log Kr0 = 5.05) and thermodynamic parameters were calculated using the data obtained by pH-metric measurements at 25.0±0.1 °C (ΔH = 10.5 kJ mol-1, ΔG = -29.0 kJ mol-1, ΔS = 133 J mol-1 K-1). [ABSTRACT FROM AUTHOR]

Aim To investigate the factors affecting metformin concentrations after chronic administration in patients with polycystic ovary syndrome (PCOS), focusing on the pharmacokinetic variability and its implications for personalized therapy. Methods This study enrolled 53 PCOS patients undergoing long-term metformin treatment at the Clinic for Gynecology and Obstetrics in Niš, Serbia, from February to December 2019. Pharmacokinetic parameters were measured from blood samples, and metformin concentrations were determined with validated analytical techniques. Results There was a significant variability in metformin concentrations among PCOS patients, with body mass index (BMI) identified as a major influencing factor. Higher BMI was associated with lower plasma metformin levels, a finding suggesting an altered pharmacokinetic profile in obese patients. Conclusions This study highlights the critical role of BMI in influencing metformin pharmacokinetics in PCOS patients and underscores the need for personalized treatment strategies in patients with PCOS. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined α-tocopherol and tocopherol acetate content in commercial pharmaceutical colostrum product via solid phase extraction and high performance liquid chromatography.

The article discusses a study which examined thiamine and riboflavin content in infant formulas available in Serbian pharmacies, as well as the level of compliance with recommended dietary intake.

A study which determined caffeine content in anti-cellulite gels through a solid-phase extraction method followed by high-performance liquid chromatography with ultraviolet-diode array detection is presented.

A study which developed a solid-phase extraction procedure for the high-performance liquid chromatography (HPLC) determination of alpha tocopheryl acetate which could be of use in the assessment of the content of this synthetic form of vitamin E in sunscreen lotions and creams, is presented.

The aim of this work is to develop a new kinetic spectrophotometric method for the determination of acetylsalicylic acid (ASA) in pharmaceutical formulations. In general, ASA analysis is not realised directly, and a previous quantitative hydrolysis in a basic medium is necessary, converting ASA to salicylate ions for its determination. The hydrolysis is carried out by sodium hydroxide solution. The method is based on a ligand-exchange reaction. The reaction was followed spectrophotometrically by monitoring the rate of disappearance of the cobalt(II)-1-nitroso-2-naphthol complex in alkaline medium at 410 nm. The optimum operating conditions regarding reagent concentrations and temperature were established. The initial-rate method is adopted for constructing the calibration curve, which was found to be linear over the concentration range 0.72-9.00 μg mL-1. The optimized conditions yielded a theoretical detection limit of 0.35 μg mL-1 based on the 3.3S0 criterion. The interference effects of certain ingredients of powdery drugs, foreign ions and amino acids upon the reaction rate were studied in order to assess the selectivity of the method. The results are validated statistically and through recovery studies. The point hypothesis test have been performed which indicate that there is no significant difference between the proposed method and the reference method. The developed procedure was successfully applied to the rapid determination of acetylsalicylic acid in commercial pharmaceutical preparations and human control serum. The unique features of this procedure are that determination can be carried out at room temperature and analysis time is short. The newly developed method is simple, inexpensive and efficient for use in the analysis of a large number of samples. [ABSTRACT FROM AUTHOR]