Condensation methodology for quantification of Polymyxin B fluorimetrically: application to pharmaceutical formulations and greenness assessment

Abstract

The appearance of multidrug-resistant Gram-negative bacterial infections, along with the lack of newly discovered antibiotics, resulted in the return to old antimicrobial medications like Polymyxins. As a result, the suggested technique aims to develop a fast, environmentally friendly, and sensitive fluorimetric method for quantifying Polymyxin B. The investigated approach depends on generating a highly fluorescent derivative by a condensation pathway between the studied drug and ninhydrin in the presence of phenylacetaldehyde and then estimated spectrofluorimetrically. After the reaction conditions were well optimized, the fluorescent product was estimated at emission wavelength (λ_em) = 475.5 nm (following excitation at a wavelength (λ_ex) = 386 nm. The developed calibration plot displayed rectilinear throughout the following range (0.2-3 µg mL^{- 1}), and the calculated limit of detection and quantification were 0.062 µg mL^{- 1} and 0.187 µg mL^{- 1}, respectively. As a consequence, the drug's ophthalmic and intravenous pharmaceutical forms were both successfully quantified with an excellent degree of recovery. Finally, the methodology's greenness was assessed utilizing Analytical Eco-Scale scores.

Keywords: Methodology’s greenness; Ninhydrin; Ophthalmic and intravenous pharmaceutical forms; Phenylacetaldehyde; Polymyxin B.

Fig. 1

Polymyxin B sulfate (Poly B) chemical structure

Fig. 2

Suggested pathway of the reaction between the investigated drug and the fluorogenic reagent

Fig. 3

Excitation and emission spectra of Poly B (2 µg mL^− 1) with fluorogenic reagents

Fig. 4

Effect of the pH and buffer volume on the RFI of the reaction product of Poly B (2 µg mL^− 1)

Fig. 5

Effect of fluorogenic reagents volumes on the RFI of the reaction product of Poly B (2 µg mL^− 1)

Fig. 6

Temperature on the RFI of the reaction product of Poly B (2 µg mL^− 1)

Fig. 7

Heating time effect on the RFI of the reaction product of Poly B (2 µg mL^− 1)

Fig. 8

Solvent type effect on the RFI of the reaction product of Poly B (2 µg mL^− 1)