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130 results on '"DAVID, Iulia Gabriela"'

5. Curcumin Electrochemistry—Antioxidant Activity Assessment, Voltammetric Behavior and Quantitative Determination, Applications as Electrode Modifier.

Author

David, Iulia Gabriela, Iorgulescu, Emilia Elena, Popa, Dana Elena, Buleandra, Mihaela, Cheregi, Mihaela Carmen, and Noor, Hassan

Subjects
CURCUMIN, VOLTAMMETRY, ELECTROCHEMISTRY, CHEMICAL species, ELECTRODES, ANTIOXIDANTS, TURMERIC
Abstract

Curcumin (CU) is a polyphenolic compound extracted from turmeric, a well-known dietary spice. Since it has been shown that CU exerts beneficial effects on human health, interest has increased in its use but also in its analysis in different matrices. CU has an antioxidant character and is electroactive due to the presence of phenolic groups in its molecule. This paper reviews the data reported in the literature regarding the use of electrochemical techniques for the assessment of CU antioxidant activity and the investigation of the voltammetric behavior at different electrodes of free or loaded CU on various carriers. The performance characteristics and the analytical applications of the electrochemical methods developed for CU analysis are compared and critically discussed. Examples of voltammetric investigations of CU interaction with different metallic ions or of CU or CU complexes with DNA as well as the CU applications as electrode modifiers for the enhanced detection of various chemical species are also shown. [ABSTRACT FROM AUTHOR]

Published
2023
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23. Simple Electrochemical Chloramphenicol Assay at a Disposable Pencil Graphite Electrode by Square Wave Voltammetry and Linear Sweep Voltammetry.

Author

David, Iulia Gabriela, Buleandră, Mihaela, Popa, Dana Elena, Bercea, Ana Maria, and Ciucu, Anton Alexandru

Subjects
*SQUARE waves, *CHLORAMPHENICOL, *GRAPHITE, *ELECTRODES, *PENCILS, *VOLTAMMETRY
Abstract

Chloramphenicol (CAP) is a widely used, broad spectrum antibiotic that contains a nitrobenzene moiety with a possible poisonous feature. Thus, the development of low cost, simple, and rapid analytical methods for the reliable CAP quantification is necessary. Starting from the nitro group electroactivity, the cyclic voltammetric properties of CAP were investigated at the common commercially available, disposable pencil graphite electrode (PGE). The effect of the electrode material, the electrolyte pH and the potential scan rate were investigated. At 2H type PGE, the CAP cyclic voltammograms presented an anodic and two cathodic diffusion controlled, pH-dependent peaks, each involving the exchange of two electrons and two protons. Based on CAP main reduction peak at PGE in pH 5.00 Britton Robinson buffer, a square wave voltammetric (SWV) method was developed for its quantification from 2.50 × 10−6 to 7.50 × 10−4 mol L−1 with a limit of detection (LoD) of 1.39 × 10−6 mol L−1. Moreover, the anodic peak was also employed for the first time for a CAP linear sweep voltammetric (LSV) assay (2.50 × 10−6 to 1.00 × 10−3 mol L−1; LoD 6.09 × 10−7 mol L−1 CAP). Both voltammetric methods using the cost-effective PGE were applied for the determination of CAP in pharmaceuticals, obtaining recoveries of 100.9 ± 1.4% (relative standard deviation of 3.54%) for SWV and 100.7 ± 1.4% (relative standard deviation of 3.55%) for LSV. [ABSTRACT FROM AUTHOR]

Published
2022
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33. Pencil Graphite Electrodes: A Versatile Tool in Electroanalysis

Author

David, Iulia Gabriela, Popa, Dana-Elena, and Buleandra, Mihaela

Subjects
Article Subject
Abstract

Due to their electrochemical and economical characteristics, pencil graphite electrodes (PGEs) gained in recent years a large applicability to the analysis of various types of inorganic and organic compounds from very different matrices. The electrode material of this type of working electrodes is constituted by the well-known and easy commercially available graphite pencil leads. Thus, PGEs are cheap and user-friendly and can be employed as disposable electrodes avoiding the time-consuming step of solid electrodes surface cleaning between measurements. When compared to other working electrodes PGEs present lower background currents, higher sensitivity, good reproducibility, and an adjustable electroactive surface area, permitting the analysis of low concentrations and small sample volumes without any deposition/preconcentration step. Therefore, this paper presents a detailed overview of the PGEs characteristics, designs and applications of bare, and electrochemically pretreated and chemically modified PGEs along with the corresponding performance characteristics like linear range and detection limit. Techniques used for bare or modified PGEs surface characterization are also reviewed.

Published
2017
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35. Voltammetric Determination of Carprofen

Author

David, Iulia Gabriela, primary, Popa, Dana Elena, additional, Buleandra, Mihaela, additional, Dan, Emilia, additional, Stan, Georgeta-Simona, additional, Badea, Irinel Adriana, additional, Iorgulescu, Emilia-Elena, additional, and Aboul Enein, Hassan Y., additional

Published
2018
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38. Microwave Assisted Batch Extraction of Polyphenols From Sea Buckthorn Leaves

Author

Asofiei, Ioana, Calinescu, Ioan, Trifan, Adrian, David, Iulia Gabriela, and Gavrila, Adina Ionuta

Subjects
food and beverages
Abstract

Extraction of polyphenols from Sea Buckthorn leaves using microwave assisted extraction (MAE) is described. The influence of different parameters on the extraction process (reactor type, stirring rate, extraction time, temperature, ethanol/water ratio) was studied. The polyphenolic extracts were analyzed in order to determine the total phenolic content (TPC) by Folin-Ciocalteu method or by differential pulse voltammetry (DPV) and the concentration of the main polyphenolic compounds by HPLC. The specific microwave energy was also determined. MAE leads to a shorter extraction time (7.5 min versus 30 min for the conventional method). The best results of MAE were obtained at a temperature of 90°C, using a solvent/plant ratio of 20/1 and 50% ethanol in the extraction solvent. The highest values of antioxidant capacity were obtained for polyphenolic extracts resulted from microwave extraction.

Published
2016
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