This study developed a nanosensor for the detection and determination of favipiravir, a presumed drug that has potential therapeutic efficacy in treating COVID‐19 patients, from tablets and serum samples. This nanosensor was obtained by adding the optimum amount of diamond nanoparticles into carbon paste. For the determination of favipiravir adsorptive stripping differential pulse (AdSDPV) and adsorptive stripping square wave voltammetry (AdSSWV) were used. Limit of detection values were found as 4.83×10−9 M and 2.44×10−7 M for bulk and 5.18×10−8 M and 4.38×10−8 M for serum samples using AdSDPV and AdSSWV, respectively. Recovery studies made of the tablet and serum produced satisfactory results.
The electrochemical behavior of atorvastatin and amlodipine at a glassy carbon electrode has been studied using different voltammetric techniques. First derivative of the ratio voltammetric methods for determination of amlodipine and atorvastatin in tablets in the presence of the other compound has been described. This technique depends on the measuring of first derivative of the ratio voltammograms of each concentration as a function of the increased concentrations. DP and SW voltammetric methods depend on first derivative of the ratio-voltammetry by measurements of the selected potentials for amlodipine and atorvastatin. The linear response was within the range of 4 Â 10 À6 -1 Â 10 À4 M for amlodipine and 2 Â 10 À6 -1 Â 10 À4 M for atorvastatin. The proposed methods have been extensively validated.
Voltammetric, chromatographic, and spectrophotometric methods were developed for the simultaneous determination of bisoprolol fumarate (BIS) and hydrochlorothiazide (HCZ). Differential pulse and square wave voltammetry techniques were used to analyze BIS and HCZ simultaneously by measuring at about 1400 and 1100 mV, respectively. RP-HPLC was the second method for simultaneous analysis of the compounds. The mixture of BIS, HCZ, and moxifloxacin as an internal standard was separated on an RP Zorbax Eclipse XDB-C18 column (150 x 4.6 mm, id, 5 microm particle size) using acetonitrile-15 mM phosphate (25+75, v/v) mobile phase at a 1.0 mL/min flow rate. The third method was based on first derivative of the ratio-spectra method obtained from the measurements of the amplitudes at 246 and 257 nm for BIS and HCZ, respectively. All the proposed methods were effectively applied for the simultaneous determination of BIS and HCZ in tablet dosage forms without any time-consuming extraction, sample preparation, or derivatization procedures.
A simple, reliable and selective differential pulse (DP) and square wave (SW) voltammetric methods at glassy carbon (GC) and boron-doped diamond (BDD) electrodes of lornoxicam in pharmaceutical dosage form and in spiked human serum samples have been developed and evaluated. The possible oxidation mechanism was discussed. The voltammetric study of the model compounds allowed elucidating the possible oxidation mechanism of lornoxicam. The dependence of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate were investigated. The oxidation of lornoxicam gave a single and irreversible peak at both electrodes. The process was found diffusion controlled. For glassy carbon electrode, the linearity of the calibration curve was obtained in range of 4x10-7 M to 2x10-5 M for DPV method and 4x10-7 M to 4x10-5 M for SWV method in 0,1 M sulphuric acid solutions. Using boron-doped diamond electrode, the plot of the calibration curve was linear between 6x10-7 M and 1x10-4 M for both voltammetric methods in pH 2 BR buffer. The repeatability, reproducibility, precision and accuracy of the proposed methods were investigated.
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