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

Sensors ◽  
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.

Ultra-Performance Liquid Chromatographic and Densitometric Methods for Sensitive Determination of Xipamide and Triamterene in Pure and Pharmaceutical Dosage Forms

2021 ◽  
Author(s):  
N V Fares ◽  
Haitham A El Fiky ◽  
Amr M Badawey ◽  
Maha F Abd El Ghany
Keyword(s):  
Acetic Acid ◽  
Flow Rate ◽  
Mobile Phase ◽  
Dosage Forms ◽  
Hplc Method ◽  
Uv Detection ◽  
Pharmaceutical Dosage Forms ◽  
Selective Determination ◽  
Liquid Chromatographic

Abstract Background Validated UPLC method and TLC densitometric method were prescribed for determination of antihypertensive components. Objectives: To establish and validate rapid and accurate Ultra performance liquid chromatographic (UPLC) and TLC densitometric methods for determination of Xipamide and Triamterene in pure and dosage forms. Methods The first method; UPLC method, depended on using Agilent Zorbax Eclipse Plus C8 (50 mm × 2.1 mm, 1.8 μm), as the column, mobile phase composed of (acetonitrile-water) (70 + 30, v/v) adjusted by acetic acid to obtain (pH 3), 0.2 mL/min flow rate and UV detection at 231.4 nm. The second method was a thin layer chromatography (TLC) densitometric method, separation was achieved by using toluene-methanol-ethyl chloride-acetic acid (7 + 2 + 1 + 0.2, v/v/v) as the mobile phase, pre coated silica gel plates as the stationary phase and UV detection at 300.0 nm. Results The obtained results were validated and statistically compared with official and reported methods. The obtained results showed high accuracy and reproducible results with excellent mean recoveries for both drugs. Conclusions The UPLC method showed shorter retention time for both Xipamide (0.88 min) and Triamterene (0.63 min), lower detection limit less than 0.055 µg/mL for both drugs with high selectivity, decreased injection volume (1 µL) and lower flow rate other than any HPLC method. Both proposed methods were sensitive, selective, and effectively applied to pure and dosage forms (Epitens®). Highlights Unprecedented sensitive, rapid, and reproducible UPLC and TLC methods were developed for selective determination of mixture of Xipamide and Triamterene with LOD less than 0.076 µg/mL for both drugs.

scholarly journals Highly Selective Determination of Dopamine in the Presence of Ascorbic Acid and Serotonin at Glassy Carbon Electrodes Modified with Carbon Nanotubes Dispersed in Polyethylenimine

2008 ◽  
Vol 8 (11) ◽  
pp. 6003-6009 ◽  
Author(s):  
Marcela C. Rodríguez ◽  
María D. Rubianes ◽  
Gustavo A. Rivas
Keyword(s):  
Carbon Nanotubes ◽  
Ascorbic Acid ◽  
Glassy Carbon ◽  
Carbon Electrodes ◽  
Acid Oxidation ◽  
Promising Alternative ◽  
Glassy Carbon Electrodes ◽  
Multi Wall Carbon Nanotubes ◽  
Selective Determination

We report the highly selective and sensitive voltammetric dopamine quantification in the presence of ascorbic acid and serotonin by using glassy carbon electrodes modified with a dispersion of multi-wall carbon nanotubes (MWCNT) in polyethylenimine, PEI (GCE/MWCNT-PEI). The electrocatalytic activity of the MWCNT deposited on the glassy carbon electrode has allowed an important decrease in the overvoltages for the oxidation of ascorbic acid and dopamine, making possible a clear definition of dopamine, serotonin and ascorbic acid oxidation processes. The sensitivities for dopamine in the presence and absence of 1.0 mM ascorbic acid and serotonin were (2.18±0.03 × 105 μAM−1 (r = 0.9998); and (2.10±0.07 × 105 μAM−1 (r = 0.9985), respectively, demonstrating the excellent performance of the GCE/MWCNT-PEI. The detection limit for dopamine in the mixture was 9.2 × 10−7 M. The R. S. D. for the determination of 50 μM dopamine using four different electrodes was 3.9% when modified with the same MWCNT/PEI dispersion, and 4.6% when using four different dispersions. The modified electrode has been successfully applied for recovery assays of dopamine in human blood serum. Therefore, the new sensor represents an interesting and promising alternative for the electrochemical quantification of neurotransmitters and other analytes of clinical interest.

scholarly journals Highly Luminescent and Biocompatible P and N Co-Doped Passivated Carbon Nanodots for the Sensitive and Selective Determination of Rifampicin Using the Inner Filter Effect

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2275 ◽  
Author(s):  
Baraa Al-Hashimi ◽  
Heshu Sulaiman Rahman ◽  
Khalid Mohammad Omer
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
Fluorescence Emission ◽  
Inner Filter Effect ◽  
Single Step ◽  
Carbon Nanodots ◽  
Pharmaceutical Dosage Forms ◽  
Selective Determination ◽  
Filter Effect

The determination of rifampicin in pharmaceutical dosage forms using a rapid, sensitive, selective, biocompatible, and low-cost method is of vital importance in the pharmaceutical analysis field to ensure its concentration is within the effective range when administered. In this study, nitrogen-and-phosphorous-doped carbon nanodots (CNDs) were prepared using a single-step hydrothermal method with ciprofloxacin as the starting material. The CNDs showed a highly intense blue fluorescence emission centered at 450 nm, with a photoluminescence quantum yield of about 51%. Since the absorption of rifampicin was the same as the excitation spectrum of CNDs, inner filter effect (IFE) quenching occurred and it was used as a successful detection platform for the analysis of rifampicin in capsules. The detection platform showed a dynamic linear range from 1 to 100 μM (R2 = 0.9940) and the limit of detection was 0.06 μM (when S/N = 3). The average spike recovery percentage for rifampicin in the capsule samples was 100.53% (n = 5). Moreover, the sub-chronic cytotoxicity of CNDs was evaluated on healthy male mice (Balb/c) drenched with different amounts of CNDs (10 and 50 mg/kg). During this study period, no mortalities or toxicity signs were recorded in any of the experimental subjects. Based on the cytotoxicity experiment, the proposed nano-probe is considered safe and biocompatible.

scholarly journals Interactive Studies on Synthetic Nanopolymer decorated with Edible Biopolymer and its Selective Electrochemical determination of L-Tyrosine

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nathiya Dhananjayan ◽  
Wilson Jeyaraj ◽  
Gurunathan Karuppasamy
Keyword(s):  
Thermo Gravimetric Analysis ◽  
Electrochemical Determination ◽  
Electrochemical Analysis ◽  
Oxidation Potential ◽  
Hydroxyl Groups ◽  
Gravimetric Analysis ◽  
Selective Determination ◽  
Adhesive Surface ◽  
Effective Role

Abstract Herein, an edible biopolymer amine Modified Gum Acacia (MGA), successfully encumbered with Electron Beam irradiated Polypyrrole Nanospheres (EB-PPy NSs), was investigated for the effective role in L-Tyrosine (Tyr) biosensing application. The morphology of EB-PPy NSs decorated MGA (EB-PPy/MGA) hybrid nanobiocomposite has been studied by Scanning electron microscopy and its affirmed interactions were characterized by X-ray diffraction, Raman, FT-IR spectroscopy, UV-Visible spectroscopy, Thermo Gravimetric Analysis and Vibrating Sample Magnetometer. The hybrid nanobiocomposite manifested diamagnetic behavior with reduced saturation magnetization (Ms = 1.412 × 10−4 emu/g) to produce more adhesive surface. Amine chains in EB-PPy NSs and hydroxyl groups of MGA contributed to effective immobilization, thus enabling suitable orientation for Tyr determination. The electrochemical analysis illustrated that the proposed nanobiocomposite based sensor exhibited an excellent electrocatalytic activity toward selective determination of Tyr in the linear range of 0.4 to 600 µM with a lower detection limit of 85 nM, low oxidation potential of 0.72 V and good selectivity. Finally, the reliability of the constructed EB-PPy/MGA for Tyr detection was demonstrated in real samples.

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