Characterization of PVA-Enzyme Coated Indicator Electrodes GA coated again with PVC-KTpClPB-o-NPOE SEM-EDS, FTIR and XRD analysis

This study aims to characterize the tungsten-urea analyte indicator electrode. The method used is biosensor potentiometry with urease enzyme immobilization technique. This indicator electrode was coated with PVA-enzyme coated with glutaraldehyde (GA) 2.9% coated with PVC-KTpClPB- o-NPOE with o-NPOE variation of 61% and 66%. Characterization of coated indicator electrodes using SEM-EDS, FTIR and XRD analysis. A1-4 61% indicator electrode sample coated PVA-enzyme 1x coated with glutaraldehyde (GA) 2.9% 1x coated PVC-KTpClPB- o-NPOE 1x, with o-NPOE 61%. A3-4 61% indicator electrode sample coated PVA-enzyme 3x coated with glutaraldehyde (GA) 2.9% 1x coated PVC-KTpClPB- o-NPOE 1x, with o-NPOE 61%. Likewise, the reasoning of samples A1-4 66% and A3-4 66%. There are four indicator electrodes made with the notation A1-4 61%, A1-4 66%, A3-4 61% and A3-4 66%. The best results were obtained at the indicator electrode sample A1-4 61%, contributing to the urea sensor of the potentiometer cell

Characterization of PVA-Enzyme Coated Indicator Electrodes GA coated again with PVC-KTpClPB-o-NPOE UV-Vis analysis, variable signal analysis, sensor sensitivity and SEM-EDS

This study aims to characterize the phosphate buffer and urease enzymes through UV-Vis and SEM-EDS absorbance spectra using tungsten as an indicator electrode. The method used is a potentiometric biosensor with urease enzyme immobilization technique for urea analyte. A small detection range of 10-5-10-4M has been studied with PVA-enzyme coated indicator electrodes coated with PVC-KTpClPB. On this basis, the researchers increased the detection range by analyzing glutaraldehyde (GA) mixed with PVA-enzyme and o-NPOE mixed with PVC-KTpClPB. The best results of GA mixed PVA-enzyme at GA2.9% UV-Visible analysis. The best results were PVA-enzyme coated indicator electrodes coated with GA coated again with PVC-KTpClPB-o-NPOE SEM-EDS analysis on PVA-enzyme samples 3x coated with GA 1x and PVC-KTpClPB-o-NPOE 1x with o-NPOE variation of 61% and 66%.

POSSIBILITIES OF IMMUNOPOTENTIOMETRY IN DIAGNOSTICS CATTLE LEUKEMIA

The article describes the results of studies to determine the difference in the electrochemical potentials of the indicator electrode in blood serum samples from healthy and infected with BLV animals before and after the formation of the CEC "in vitro". In the blood serum of healthy cows, potentiometric parameters change after the addition of the BLV antigen by no more than 0.05 units, and in blood serum samples from cows infected with the virus, under the same conditions, by 0.15 or more units. Measurement of the potential of the indicator electrode in the studied blood serum sample before and after the formation of immune complexes can serve as the basis for diagnostic studies in cattle leukemia and other infectious diseases.

Potentiometric Determination of Prednisolone in Pharmaceutical Formulations

In this present work, a prednisolone ion selective electrode (PRED-ISE) has been developed. The electrode shows linear response towards prednisolone in the range 3.0×10−6 – 8.6×10−3 M with a detection limit of 2.5×10−6. PRED-ISE was used as an indicator electrode for the potentiometric titration of different concentrations of standard prednisolone against standardized sodium tetraphenyl borate solution and in tablets. The electrode manifests advantages of low resistance, fast response and, most importantly, good selective relativity to a variety of other cations.

Potentiometric Titration of Vanadium (V) with Iron (II) in the Presence of NTA and DTPA Using Dry-Cell Graphite Electrode

A sensitive potentiometric titration for vanadium (V) based effect of ligands such as nitrilotriacetic acid (NTA) and diethylenetriaminepenta-acetic acid (DTPA) are reviewed. The potential iron system decreased the presence of NTA and DTPA. In this case, iron (III) increased with respect to the vanadium (IV) volume. The production of iron (III)-ligand complex has increased. This result suggested that the formation of V(V)-NTA and V(V)-DTPA complexes were less favoured than that of V(IV)-NTA and V(IV)-DTPA complexes. The calculated correlation coefficients (r) conveyed the effectiveness of the graphite electrode as the indicator electrode for the potentiometric titrations. On comparing the potential jump values, the extent of potential caused by DTPA was found to be more than that of NTA. The utilization of graphite electrode has facilitated the potentiometric titration by significantly causing larger potential jump. This method was precise and accurate as no interference of foreign ions was observed. Hence, the approach could be applied to the vanadium (V) of any samples.

The Use of Tungsten in Potentiometry to Detect Pospat Baffer and Urease Enzyme

This study aims to characterize phosphate buffer and urease enzymes through the absorbance spectrum of UV-Vis and FTIR using tungsten as the indicator electrode. The method used in this research is the biosensor potentiometric method carried out in the Laboratory of the Faculty of Mathematics and Natural Sciences, State University of Medan and the Beacukai Belawan Medan laboratory. The absorbance characterization of electrolyte solutions in various compositions using UV-Vis showed that phosphate buffer solution 0.001 M pH 7.5+KCl 0.001 M + urea 0.001 M+3 drops urease enzyme had the highest absorbance compared to electrolyte solutions with phosphate buffer and urea content. Likewise, the FTIR results showed the same thing where phosphate buffer solution was 0.001 M pH 7.5 + KCl 0.001 M + urea 0.001 M + 3 drops urease enzyme had the highest% T (transmission) pattern of phosphate buffer solution and urea. The urease enzyme in this study functions as a catalyst. Based on UV-Vis and FTIR characterization, it was concluded that the phosphate buffer solution of 0.001 M pH 7.5+KCl 0.001 M + urea 0.001 M + 3 drops of urease enzyme was the best.

Design and Characterization of Electrochemical Sensor for the Determination of Mercury(II) Ion in Real Samples Based upon a New Schiff Base Derivative as an Ionophore

The present paper provides a description of the design, characterization, and use of a Hg2+ selective electrode (Hg2+–SE) for the determination of Hg2+ at ultra-traces levels in a variety of real samples. The ionophore in the proposed electrode is a new Schiff base, namely 4-bromo-2-[(4-methoxyphenylimino)methyl]phenol (BMPMP). All factors affecting electrode response including polymeric membrane composition, concentration of internal solution, pH sample solution, and response time were optimized. The optimum response of our electrode was obtained with the following polymeric membrane composition (% w/w): PVC, 32; o-NPOE, 64.5; BMPMP, 2 and NaTPB, 1.5. The potentiometric response of Hg2+–SE towards Hg2+ ion was linear in the wide range of concentrations (9.33 × 10–8−3.98 × 10–3 molL–1), while, the limit of detection of the proposed electrode was 3.98 × 10–8 molL–1 (8.00 μg L–1). The Hg2+–SE responds quickly to Hg2+ ions as the response time of less than 10 s. On the other hand, the slope value obtained for the developed electrode was 29.74 ± 0.1 mV/decade in the pH range of 2.0−9.0 in good agreement with the Nernstian response (29.50 mV/decade). The Hg2+–SE has relatively less interference with other metal ions. The Hg2+–SE was used as an indicator electrode in potentiometric titrations to estimate Hg2+ ions in waters, compact fluorescent lamp, and dental amalgam alloy and the accuracy of the developed electrode was compared with ICP–OES measurement values. Moreover, the new Schiff base (BMPMP) was synthesized and characterized using ATR–FTIR, elemental analysis, 1H NMR, and 13C NMR. The PVC membranes containing BMPMP as an ionophore unloaded and loaded with Hg(II) are reported by scanning electron microscope images (SEM) along with energy-dispersive X-ray spectroscopy (EDX) spectra.

Investigation of the components nature and concentration influence on carbon dioxide equilibrium in the system CaCl2-Na2CO3-NaOH-H2O by potentiometric titration

The modern thermal power plants equipment requires strict deposits control on the surfaces. Such deposits are formed from impurities entering the cycle with water, the amount of which has significantly increased at modern powerful thermal power plants. At the modern level of the coolant water treatment, it is possible to exclude most of the impurities responsible for salt deposition. Analysis of various types of the sediments has shown that carbonate deposits are an integral part of them. Modern research methods (potentiometric titration in combination with methods of mathematical modelling) for carbonate, silicate, phosphate water systems have shown the existence of phase-unstable states leading to salt deposition during the coolant circulation. In this article, the carbonate system CaCl2-Na2CO3-NaOH-H2O was studied by potentiometric titration with a glass indicator electrode. The influence of the components nature (Li2CO3, Na2CO3, Ca2CO3, LiOH, NaOH, KOH, CaCl2, MgCl2) and the conditions for the existence of phase-unstable systems with varying concentrations of these components were studied. It is known that organic phosphonates are effective inhibitors of deposits in the carbonate system. In this paper, the action of two compounds of the specified class is considered. The concentration limits of their inhibitory action have been determined.

PORTABLE AMPEROMETRIC SENSOR FOR MEASURING THE TOTAL ANTIOXIDANT ACTIVITY OF SUBSTANCES

Understanding the role of antioxidants as substances interrupting free radical reactions intensifies the search for new natural and synthetic substances with antioxidant properties. Along with this, intensive research is underway to create methods for assessing the antioxidant (AO) properties of various substances and devices for determining antioxidant activity (AOA). This article proposes an amperometric method and a sensor for measuring the total antioxidant activity of substances. The method is based on the process of oxygen electroreduction in the absence and presence of antioxidants of various origins in the solution. The measurement of the analytical signal before and after the introduction of the antioxidant substance into the electrochemical cell is carried out using a portable two-electrode sensor, "pencil" type, with a silver cathode, on which a potential of -500 mV is applied from a DC source (batteries). As an antioxidant standard, a 1% solution of ascorbic acid in a phosphate buffer with a pH of 6.86 was conventionally adopted. The sensor is connected to the measuring and driving device through a microcircuit - an operational amplifier. The measured signal in arbitrary units is displayed on the liquid crystal screen of the setting and measuring device and characterizes the maximum depolarization current of the indicator electrode. Using the resistors of the measuring device, a range of 0 - 100 units is set, for the analyte in the absence of an antioxidant and in the presence of a standard - 1% ascorbic acid solution, conventionally taken as 100%, respectively. Thus, the antioxidant activity of substances can be measured as a percentage relative to ascorbic acid (or other antioxidant). The results of determining the total antioxidant activity of some drinks and aqueous-alcoholic extracts of medicinal plants are presented.

Study of the Complex Formation Process in the Iron (III)-1-Phenyl-2,3-Dimethylpyrazolin-5-Thion-6 mol/l HCl + Acetone System by the Potentiometric Method

The complex formation of iron (III) ions in a wide range of temperatures in a mixed solvent was studied by the potentiometric method using a redox electrode based on 1-phenyl-2,3-dimethylpyrazoline-5-thione and its oxidized form. The study shows that titration of the iron (III)--1-phenyl-2,3-dimethylpyrazoline-5-thione--6 mol/l HCl (HCl + acetone, ratio 1:3) system at a temperature of 273--318 K results in a regular increase in the potential indicator electrode. It was found that in the system under consideration four complex forms of compositions are formed: [FeL(H2O)5]3+, [FeL2(H2O)4]3+, [FeL3(H2O)3]3+ and [FeL4(H2O)2]3+. For each complex particle, their stability constants are determined by the Bjerrum method. Summarizing the experimental and theoretical data, it was established that the iron (III) complexes obtained in the 6 mol/l HCl medium are more stable than the complexes obtained in a mixed solvent with 1-phenyl-2,3-dimethylpyrazoline-5-thione. The values ΔH and ΔG of reactions of the formation of 1-phenyl-2,3-dimethylpyrazoline-5-thione complexes were found by Clark --- Glu method using the regression method. The corresponding patterns in the change in values ΔH, ΔG and ΔS of formation of complexes were revealed. To determine the region of dominance and the maximum yield of a particular complex particle, depending on the concentration of the organic ligand in the solution, distribution diagrams were constructed, according to which the maximum yield of a complex particle and the region of its dominance can be found at any point The work was carried out in accordance with the research plan of the laboratory "Synthesis and testing of coordination compounds" named after Corresponding Member of Tajik Academy of Sciences, Dr. Sc. (Chem.), Professor A.A. Aminjanov, Research Institute of the Tajik National University (project no. 0119TJ01007)