A Convenient Apparatus for Electrometric Titration Depending on the Change of Oxidation Potential, and Its Application to the Determination of Small Quantities of Chromium in Steel

Zinc oxide (ZnO) nanoparticles with an average size of 60 nm have been successfully prepared by microwave irradiation. Carbon paste electrode (CPE) was modified with ZnO nanoparticles and used for the electrochemical oxidation of chlorpheniramine maleate (CPM). Cyclic voltammetry (CV) study of the modified electrode indicated that the oxidation potential shifted towards a lower potential by approximately 106 mV and the peak current was enhanced by 2 fold in comparison to the bare CPE (ZnO/CPE-CV). The electrochemical behaviour was further described by characterization studies of scan rate, pH and concentration of CPM. Under the optimal conditions, the peak current was proportional to CPM concentration in the range of 8.0 ×10-7 to 1.0 × 10-3 mol L-1 with a detection limit of 5.0 × 10-7 mol L-1 by differential pulse voltammetry (DPV). The peak current of CPM is linear in the concentration range of 0.8 - 1000 µM (R2=0.998). The ZnO/CPE has good reproducibility and high stability for the determination of CPM using this electrode. The proposed method was successfully applied to the determination of CPM in pharmaceutical samples. In addition, the important analytical parameters were compared with other methods which show that ZnO/CPE-CV procedure is comparable to recently reported methods.

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Cerium(IV) and Iron(III) Oxides Nanoparticles Based Voltammetric Sensor for the Sensitive and Selective Determination of Lipoic Acid

Sensors ◽

10.3390/s21227639 ◽

2021 ◽

Vol 21 (22) ◽

pp. 7639

Author(s):

Guzel Ziyatdinova ◽

Liliya Gimadutdinova

Keyword(s):

Lipoic Acid ◽

Inorganic Ions ◽

Fold Increase ◽

Living Organism ◽

Oxidation Potential ◽

Acid Oxidation ◽

Voltammetric Sensor ◽

Pharmaceutical Dosage Forms ◽

Selective Determination

A novel voltammetric sensor based on СеO2·Fe2O3 nanoparticles (NPs) has been developed for the determination of lipoic acid, playing an essential role in aerobic metabolism in the living organism. Sensor surface modification provides a 5.6-fold increase of the lipoic acid oxidation currents and a 20 mV anodic shift of the oxidation potential. The best voltammetric parameters have been obtained for the 0.5 mg mL−1 dispersion of СеO2·Fe2O3 NPs. Scanning electron microscopy (SEM) confirms the presence of spherical NPs of 25–60 nm, and their aggregates evenly distributed on the electrode surface and formed porous coverage. This leads to the 4.4-fold increase of the effective surface area vs. bare glassy carbon electrode (GCE). The sensor shows a significantly higher electron transfer rate. Electrooxidation of lipoic acid on СеO2·Fe2O3 NPs modified GCE is an irreversible diffusion-controlled pH-independent process occurring with the participation of two electrons. The sensor gives a linear response to lipoic acid in the ranges of 0.075–7.5 and 7.5–100 μM with the detection limit of 0.053 μM. The sensor is selective towards lipoic acid in the presence of inorganic ions, ascorbic acid, saccharides, and other S-containing compounds. The sensor developed has been tested on the pharmaceutical dosage forms of lipoic acid.

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Voltammetric Characterization of the Behavior of Biologically Active Compound Enoxil in Various Media

Chemistry Journal of Moldova ◽

10.19261/cjm.2011.06(1).09 ◽

2011 ◽

Vol 6 (1) ◽

pp. 62-68

Author(s):

Gheorghe Nemţoi ◽

Tudor Lupaşcu ◽

Alexandra Ciomaga ◽

Alexandru Cecal

Keyword(s):

Sodium Perchlorate ◽

Reduction Process ◽

Oxidation Potential ◽

Biologically Active ◽

Aqueous Environment ◽

Cathodic Current ◽

Oxidation Reduction ◽

Complex Preparation

This paper presents the results of scientific research related to the electrochemical behavior of the complex preparation Enoxil. It was established that the oxidation-reduction process of Enoxil is quasireversible. The reactivity of Enoxil obtained from alcohol soluble enotannins is more pronounced, compared to that obtained from standard enotannins. The dependence of cathodic current intensity on Enoxil concentration is linear. This can be used to establish Enoxil concentration in solution. Cyclic voltamograms were used to establish reduction and oxidation potential and the formal redox potential on platinum electrode in sodium perchlorate aqueous environment. These features can be used for identification and determination of Enoxil in pharmaceuticals.

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The Determination of the Solubility of Silver Chloride by an Electrometric Titration Method

Journal of the American Chemical Society ◽

10.1021/ja01306a022 ◽

1935 ◽

Vol 57 (3) ◽

pp. 459-465 ◽

Cited By ~ 7

Author(s):

Alfred S. Brown ◽

D. A. MacInnes

Keyword(s):

Silver Chloride ◽

Titration Method ◽

Electrometric Titration

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Studies on soil reaction: VI. The interaction of acid soils, calcium carbonate and water, in relation to the determination of “lime requirements.”

The Journal of Agricultural Science ◽

10.1017/s0021859600005700 ◽

1925 ◽

Vol 15 (2) ◽

pp. 237-255 ◽

Cited By ~ 4

Author(s):

Edward M. Crowther ◽

Wallace S. Martin

Keyword(s):

Calcium Concentration ◽

Empirical Relationship ◽

Acid Soils ◽

Soil Reaction ◽

Titration Curves ◽

Calcium Bicarbonate ◽

Electrometric Titration ◽

Single Determination ◽

Bicarbonate Solutions

The variations in Hutchinson-MacLennan “lime requirement” with the amount of soil and calcium bicarbonate solution are shown to be connected with the buffer action of the soil. Indirect titration curves can be derived from the calcium bicarbonate results, and show a systematic divergence from the direct electrometric titration curves, owing to the variable calcium concentration of the final bicarbonate solutions. In the presence of calcium chloride both methods show lower pH values for a given base absorption and yield almost identical titration curves. The Hutchinson-MacLennan “lime requirement” is always less than the equivalent of the amount of calcium hydroxide necessary to give a neutral suspension in the electrometric titrations. The calcium bicarbonate solutions at equilibrium are always more acid than pH 6·2, but the “salt effect” tends to give results corresponding to a somewhat higher degree of neutralisation. “Lime requirements” should be obtained by interpolation to some arbitrary concentration, and an empirical relationship is given by which the interpolation may be made from a single determination. The Hutchinson-MacLennan method can give no indication of the intensity of soil acidity, but serves to estimate the amount of lime necessary to give a considerable reduction of acidity.

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