DETERMINATION OF CALCIUM CONTENT IN DIETARY SUPPLEMENTS

Calcium is a macro element that is very important for the human body: its content and circulation in the body is large, it serves as the electrolyte, it has a building role and participates in the process of metabolism. The European Union, the World Health Organization (WHO) and the Ministry of Food and Drug (Food and Drug Administration, FDA) gave the RDA (Recommended Dietary Allowances,) for this macro element. The absorption and bioavailability of the calcium may vary depending on a number of factors, and because all of the foregoing it is consumed by means of different supplements. The aim of this study was to determine the content of calcium in the various diet products using the volumetric analytical method of analysis. Supplements that were analyzed are divided into two groups. The first group consists supplements in which the calcium is present in the form of different chemical compounds, and the second group consists of supplements of a number of different manufacturers in which the calcium is in the form of calcium carbonate. Calcium content, obtained by applying the method above, which ranged from 95.11% to 99.80% compared to the theoretical value. Results were analyzed using the t-test, while not producing a statistically significant difference

Synthesis and Characterization of MnCo2O4 Porous Spinel Oxide

This work presents an investigation on spinel structured material that consist of Mn(II) and Co(II) combined in the formula MnCo2O4, where Mn(II) occupies tetrahedral and Co(II) octahedral sites of crystal structure. Such spinel structured material, MnCo2O4 was synthesized by citrate-gel combustion (CGC) technique, carefully chosen as the method of synthesis is very important for producing a material with desirable physico-chemical characteristics

Determination of diazepam by flow-injection with amperometric detection in beverages

Diazepam belongs to the group of benzodiazepine drugs, and its consumption with alcohol enhances its sedative effect and absorption rate. That is why it is often used as “date rape drug” [1]. In our experiments we applied the flow injection system on diazepam determination on a bare glassy carbon electrode. The electrochemical determination of diazepam is based on reduction of the azomethine group yielding a dyhidrodiazepam. The single cathodic peak is caused by the reduction of diazepam by a two electron change. The reduction potential is highly dependent on pH value of the electrolyte, shifting to more negative potentials with higher pH [2]

Development of a Flow Injection System for Differential Pulse Amperometry and Its Application for Diazepam Determination

The is work presents the development of a flow injection system for differential pulse amperometry (DPA) for diazepam determination in the presence of oxygen. The thin flow cell consisted of the bare glassy carbon electrode, reference silver/silver chloride, and stainless steel as the auxiliary electrode. Electrochemical reduction of diazepam (DZP) was characterised by cyclic voltammetry. Azomethine reduction peak was used for DZP quantification. The detector response was linear in the range 20-250 mu mol/dm(3) of diazepam, with a calculated detection limit of 3.83 mu g/cm(3). Intraday and interday precision were 1.53 and 10.8%, respectively. The method was applied on three beverage samples, energetic drink, and two different beer samples, and obtained recoveries were from 93.65 up to 104.96%. The throughoutput of the method was up to 90 analyses per hour

Voltammetric determination of diazepam on antimony film screen-printed electrode in pharmaceutical formulations

Background: Diazepam belongs to the group of 1,4-benzodiapines. It is used for the treatment of anxiety, convulsions and as a muscle relaxant. The presence of 4,5-azomethine group enables its electrochemical detection.Introduction: A screen-printed electrode modified with antimony film was used for the determination of diazepam in pharmaceutical preparationsMethods: Electrode modification was done by ex-situ deposition of antimony on commercially available screen-printed electrode. Parameters affecting the electroanalytical response of the sensor, such as deposition potential, deposition time, and antimony concentration, were examined and optimized. The modified electrode showed enhanced electroactivity for diazepam reduction compared to unmodified electrode. Under optimal conditions, linear sweep voltammetry was used for the determination of analyte.Results: The sensor showed linear dependence in the range from 0.5 to 10 μmol/L, the correlation coefficient was 0.9992. The limit of detection was 0.33 μmol/L, corresponding limit of quantification was 1.08 μmol/L. Modification enabled determination of diazepam in the presence of oxygen. Conclusion: The modified electrode was used for the determination of diazepam in tablets. Results confirmed the applicability of the electrochemical sensor.This is the peer-reviewed version of the article: Vesna, A.; Rada, B.; Aleksandar, L. Voltammetric Determination of Diazepam on Antimony Film Screen- Printed Electrode in Pharmaceutical Formulations. Current Pharmaceutical Analysis 2021, 17 (7), 945–950. [https://doi.org/10.2174/1573412916999200730234925

Voltammetric determination of lead and copper in wine by modified glassy carbon electrode

This paper describes the determination of Pb and Cu with a Nafion-modified glassy carbon electrode and MnCo2O4 nanoparticles as working electrode for anodic stripping voltammetry. Pb and Cu were accumulated in HCl/KCl (0.1 mol dm-3) at a potential of -1.4 V (vs. Ag/AgCl electrode) for 480 s, followed by a linear sweep anodic stripping voltammetry (ASV) scan from -1.0 to +0.5 V. Under optimum conditions, the calibration curves were linear in the range of 0.01 - 8 and 0.01 - 5 mg dm-3 for Pb and Cu, respectively. Effect of sample dilution, accumulation time and potential were optimized. A study of interfering substances was performed. A significant increase in current was obtained at the modified electrode in comparison with the bare glassy carbon electrode. The modified electrode was successfully applied for determination of Pb and Cu in wine samples after a simple preparation procedure. Pb and Cu content in wine was used for estimation of the target hazard quotient (THQ) values for minimal and maximal levels of the metals

Effect of substituents on prediction of TLC retention of tetradentate Schiff bases and their Copper(II) and Nickel(II) complexes

The objectives of this study were to gain insights into structure-retention relationships and to propose the model to estimating their retention. Chromatographic investigation of series of 36 Schiff bases and their copper(II) and nickel(II) complexes was performed under both normaland reverse-phase conditions. Chemical structures of the compounds were characterized by molecular descriptors which are calculated from the structure and related to the chromatographic retention parameters by multiple linear regression analysis. Effects of chelation on retention parameters of investigated compounds, under normal-and reverse-phase chromatographic conditions, were analyzed by principal component analysis, quantitative structure-retention relationship and quantitative structure-activity relationship models were developed on the basis of theoretical molecular descriptors, calculated exclusively from molecular structure, and parameters of retention and lipophilicity.Peer-reviewed manuscript: [http://cherry.chem.bg.ac.rs/handle/123456789/2982

Synthesis, characterization, and biological activity of amino acid derivatives of the heteropolytungstophosphoric acid

Compounds of phosphotungstic acid (WPA) containing the amino acids alanine (WPA-Ala) or glycine (WPA-Gly) as counter cations were synthesized and characterized by elemental analysis, thermal analysis, and IR spectroscopy. Cellular toxicity was assessed by the trypan blue exclusion method, and the antiviral activity of WPA and the modified WPA compounds was tested against herpes simplex viruses (HSV) type 1 and type 2. Biological assays indicate that the newly synthesized compounds exhibit no evident cytotoxic effects on Vero cells and negligible antiviral activity against HSV-1 and HSV-2