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Spectrochim Acta A Mol Biomol Spectrosc ; 270: 120802, 2022 Apr 05.
Article in English | MEDLINE | ID: covidwho-1593067


Ascorbic acid has recently been extensively used due to its role in the management of COVID-19 infections by stimulating the immune system and triggering phagocytosis of the corona virus. The currently used spectrofluorometric methods for determination of ascorbic acid require using derivatizing agents or fluorescent probes and suffer from a number of limitations, including slow reaction rates, low yield, limited sensitivity, long reaction times and high temperatures. In this work, we present a highly sensitive spectrofluorometric method for determination of ascorbic acid by switching-on the fluorescence of salicylate in presence of iron (III) due to a reduction of the cation to iron (II). The addition of ascorbic acid resulted in a corresponding enhancement in the fluorescence intensity of iron (III)-salicylate complex at emission wavelength = 411 nm. The method was found linear in the range of 1-8 µg/mL with a correlation coefficient of 0.9997. The limits of detection and quantitation were 0.035 µg/mL and 0.106 µg/mL, respectively. The developed method was applied for the determination of ascorbic acid in the commercially available dosage form; Ruta C60® tablets. The obtained results were compared with those obtained by a reported liquid chromatographic method at 95% confidence interval, no statistically significant differences were found between the developed and the reported methods. Yet, the developed spectrofluorometric method was found markedly greener than the reference method, based on the analytical Eco-scale and the green analytical procedure index. This work presents a simple, rapid and sensitive method that can possibly be applied for determination of ascorbic acid in pharmaceuticals, biological fluids and food samples.

Ascorbic Acid , COVID-19 , Humans , SARS-CoV-2 , Spectrometry, Fluorescence , Tablets
Spectrochim Acta A Mol Biomol Spectrosc ; 249: 119241, 2021 Mar 15.
Article in English | MEDLINE | ID: covidwho-1065570


The present work describes development of rapid, robust, sensitive and green spectrofluorimetric method for determination of favipiravir (FAV). Different factors affecting fluorescence were carefully studied and Box Behnken Design was applied to optimize experimental parameters. The proposed method is based on measuring native fluorescence of FAV in 0.2 M borate buffer (pH 8.0) at 432 nm after excitation at 361 nm. There was a linear relationship between FAV concentration and relative fluorescence intensity over the range 40-280 ng/mL with limit of detection of 9.44 ng/mL and quantitation limit of 28.60 ng/mL. The method was successfully implemented for determination of FAV in its pharmaceutical formulation with mean % recovery of 99.26 ± 0.87. Moreover, the high sensitivity of the method allowed determination of FAV in spiked human plasma over a range of 48-192 ng/mL. The proposed spectrofluorimetric method was proved to be eco-friendly according to analytical eco-scale.

Amides/blood , Antiviral Agents/blood , COVID-19/blood , COVID-19/drug therapy , Pyrazines/blood , Spectrometry, Fluorescence/methods , Amides/analysis , Amides/therapeutic use , Antiviral Agents/analysis , Antiviral Agents/therapeutic use , Blood Chemical Analysis/methods , Blood Chemical Analysis/statistics & numerical data , Humans , Limit of Detection , Pyrazines/analysis , Pyrazines/therapeutic use , SARS-CoV-2 , Sensitivity and Specificity , Spectrometry, Fluorescence/statistics & numerical data