Determination of Total Antioxidant Content in Various Drinks by Amperometry

In the present work the total content of phenolic antioxidants in juice of some fruit and vegetables, in wines, water extracts of tea and herb were measured by amperometry. Efficiency of the method allowed determining the total antioxidant content in their binary and multimixes, including processes of frosting-defrosting and juice diluting as well. The deviation of experimentally received values of the total antioxidant content in some drink mixes from the values calculated proceeding from the additivity principle of the antioxidant content in separate drinks has been revealed

Voltammetric Sensor for Total Cholesterol Determination

We report on a voltammetric sensor for the detection of total cholesterol. The sensor was fabricated by co-immobilization of two enzymes: cholesterol oxidase (ChOx) and horseradish peroxidase (HRP) on porous graphite. The electrochemical behavior of the sensor was studied with the use of linear sweep voltammetry. It has been shown that the sensor has high stability and high sensitivity (16 muA mM{-1} cm{-2}). The biosensor exhibited a wide linear range up to 300 mol/dm3 in a condition close to physiological (pH=6.86). Besides, the interferences of some key analytes containing in the blood were studied. As a matter of fact, making a fabricated sensor is rather promising for using in clinical practice

Fluorescence Analysis of E. coli Bacteria in Water

The fluorescence analysis of Escherichia coli (E. coli) bacteria was done. It has been established that a luminescent signal from the one of metabolites (reduction form of nicotinamide adenine dinucleotide, NADH) can be adopted as a vitality indicator of the bacteria. This signal was chosen as an analytical signal. It was determined that the nature of this signal is fluorescence. In order to eliminate influence of the light scattering on this fluorescence signal optimal conditions were chosen

Investigation of Coenzyme Q[10] by Voltammetry

A simple, accurate and rapid voltammetric method has been developed for the quantitative determination of coenzyme Q[10]. Studies with direct current voltammetry were carried out using a glassy carbon electrode (GCE) in a phosphate buffer solution (pH 6.86). A well-defined oxidation peak of CoQ[10] was obtained at -0.600 V vs Ag/AgCl. The magnitude of the oxidation peak current has been found to be related to the concentration of the coenzyme over the range of (2.0x10{-5} to 2.0x10{-4} M) (r=0,991). Antioxidant activity of CoQ[10] was investigated

The Study of Redox Electrode Processes of Sulfur-Containing Compounds by Voltammetry

In this work the general case of quasi-reversible redox electrode processes of thiol compounds proceeding on a mercury-film electrode via a CE (chemical-electrochemical) mechanism has been revealed and investigated by voltammetry. The quantitative criteria for correlation between theory and experiment corresponding to a CE mechanism and new approach for estimating the kinetic parameters of the preceding chemical reaction have been suggested

Water Purification with Natural Sorbents: Effect of Surface Modification with Nano-structured Particles

Modified nanostructured sorbents are widely used in water treatment processes. In this work, aluminum and iron particles prepared by electro-spark dispersion have been applied as modifiers. Zeolite samples from "Holinskoe" mineral deposit (Russia, Republic of Buryatia), with a size smaller than 0.1 mm, have been modified with aluminum and iron particles, using a sol-gel process. The properties of the modified materials have been determined by means of sorption test, when removing ions Pb{2+}, Fe{3+} and Cd{2+} from the model solutions in static conditions. Using the method of thermal desorption of nitrogen (BET) it has been shown that increasing the iron content in the samples of nanostructured modified sorbents does not affect the increase in specific surface area and pore volume of the samples. Ions concentrations have been analyzed by stripping voltammetry and photocolorimetry. As a result, modified sorbents revealed a high efficiency sorption of heavy metals

Preparation and Investigation of Silver Nanoparticle–Antibody Bioconjugates for Electrochemical Immunoassay of Tick-Borne Encephalitis

A new simple electrochemical immunosensor approach for the determination of antibodies to tick-borne encephalitis virus (TBEV) in immunological products was developed and tested. The assay is performed by detecting the silver reduction signal in the bioconjugates with antibodies (Ab@AgNP). Here, signal is read by cathodic linear sweep voltammetry (CLSV) through the detection of silver chloride reduction on a gold–carbon composite electrode (GCCE). Covalent immobilization of the antigen on the electrode surface was performed after thiolation and glutarization of the GCCE. Specific attention has been paid to the selection of conditions for stabilizing both the silver nanoparticles and their Ab@AgNP. A simple flocculation test with NaCl was used to select the concentration of antibodies, and the additional stabilizer bovine serum albumin (BSA) was used for Ab@AgNP preparation. The antibodies to TBEV were quantified in the range from 50 IU·mL?1 to 1600 IU·mL?1, with a detection limit of 50 IU·mL?1. The coefficient of determination (r2) is 0.989. The electrochemical immunosensor was successfully applied to check the quality of immunological products containing IgG antibodies to TBEV. The present work paves the path for a novel method for monitoring TBEV in biological fluids

Voltammetric Study of the Total Activity of Antioxidants in the Blood Serum of Patients with Neurological Diseases

One of the main directions in the development of modern electroanalytical chemistry is the development of new effective methods for research and analysis of biological objects, particularly, human blood serum. The creation of new electrochemical sensors is a promising approach, which has determined several main directions in applied voltammetry in the field of chemical analytical control. In this work, the dynamics and parameters of total antioxidant activity of human serum blood of patients with chronic cerebral ischemia, during treatment with pharmaceutical drugs Mexidol, Cavinton Comfort, and Cytoflavin was tested by cathode voltammetry with a model process of oxygen electroreduction, using a new electrochemical sensor

Electrochemical oxidability of antioxidants: Synergism and antagonism in mixes

Aims: To investigate electrochemical oxidability of antioxidants to reveal synergistic and antagonistic effects in mixes. Materials and Methods: Electrochemical oxidability of some widely used antioxidants, including uric acid, glutathione, trolox, ascorbic acid, gallic acid, Mexidol, and potassium fenozan, was investigated by the amperometric approach. Results: All obtained electrochemical oxidability values correlate well with antioxidant activity parameters of the same compounds measured by other methods. The measurements of the electrochemical oxidability for binary mixes of substances were tested to reveal any synergistic actions. The experimental results and calculated values overlap for various combinations of tested mixes. It testifies to the absence of interaction between them (both synergism and antagonism) in the oxidation process. Conclusions: The constants of oxidation were defined for different antioxidants and mixes by amperometric approach. Most mixes of probed compounds revealed absence of interaction between them in oxidation process. In some cases (mainly with glutathione and ascorbic acid), antagonism takes place, deteriorating effects of their joint application. Apparently, a partial reduction of glutathione by ascorbic acid leads to excess of the measured value over calculated value

Antioxidant Properties of New Phenothiazine Derivatives

Phenothiazine and its derivatives have a number of properties that contribute to their wider practical use in the production of biologically active substances, drugs, dyes, etc. Therefore, the synthesis and study of new compounds is of great relevance. The aim of this work was to investigate the antioxidant activity of a number of new phenothiazine derivatives. The patterns of electroreduction of oxygen and its radicals in the presence of phenothiazine derivatives in aqueous ethanol media were studied by voltammetry. The influence of various factors on antioxidant activity was considered by the methods of experiment planning. The optimal conditions for the manifestation of the antioxidant activity of phenothiazine derivatives have been found, which seems to be relevant since it opens up new possibilities for their further use as complex preparations with antioxidant activity, including in psychiatric practice