Experimental design approach for development of spectrofluorimetric method for determination of favipiravir; a potential therapeutic agent against COVID-19 virus: Application to spiked human plasma

Graphical abstract

Highlights:

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  The first spectrofluorimetric method for determination of favipiravir which is a potential treatment of COVID-19 virus.

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  The developed method is simple, rapid, robust and sensitive.

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  Experimental design has been applied during optimization to ensure robustness of the method.

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  The excellent sensitivity of the method allowed the determination of favipiravir in human plasma.

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  Assessment of greenness of the proposed method using the analytical eco-scale.

Abstract

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.