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Complexation-based spectrofluorimetric method for besifloxacin determination: Combined experimental and computational
Abobakr A Mohamed1, Raed M Maklad2, Abdallah M Zeid3
1Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Fayoum University, 63514, Egypt.
Analytica Chimica Acta
|September 3, 2025
Summary
A new spectrofluorimetric method enhances besifloxacin hydrochloride (Bfln.HCl) fluorescence using acetate buffer. This cost-effective technique, validated by DFT calculations, offers sensitive Bfln.HCl analysis in pharmaceutical and biological samples.
Area of Science:
- Analytical Chemistry
- Pharmaceutical Analysis
- Spectroscopy
Background:
- Fluorescence methods are sensitive and cost-effective for pharmaceutical analysis.
- Besifloxacin hydrochloride (Bfln.HCl), an antibiotic for eye infections, shows enhanced fluorescence in acidic conditions.
- The mechanism of Bfln.HCl fluorescence enhancement in acidic media requires further investigation.
Purpose of the Study:
- To develop a novel spectrofluorimetric method for enhanced Bfln.HCl fluorescence.
- To elucidate the mechanism behind Bfln.HCl fluorescence enhancement.
- To validate the method for analyzing Bfln.HCl in pharmaceutical and biological samples.
Main Methods:
- Development of a spectrofluorimetric method using acetate buffer (pH 4.0) to enhance Bfln.HCl fluorescence.
- Investigation of fluorescence changes (wavelength shift, intensity increase) upon buffer addition.
- Application of Density Functional Theory (DFT) and thermodynamic analysis to understand the complex formation and fluorescence enhancement mechanism.
- Validation of the method using ophthalmic preparations and artificial aqueous humor.
Main Results:
- A 10 nm redshift in excitation wavelength and increased fluorescence intensity at 440 nm were observed.
- DFT calculations indicated the formation of stable 1:2 cyclic complexes between Bfln+ and acetic acid (AcOH), correlating with fluorescence enhancement.
- The method exhibited high sensitivity (LOD = 22.6 ng mL⁻¹), linearity (100-1000 ng mL⁻¹), and selectivity.
- Successful application to real samples (ophthalmic preparations, artificial aqueous humor) with high recovery rates.
Conclusions:
- The developed spectrofluorimetric method offers a sensitive, cost-effective, and environmentally sustainable alternative for Bfln.HCl determination.
- The study provides experimental and computational insights into the fluorescence enhancement mechanism of Bfln.HCl.
- This approach can potentially be extended to analyze other fluoroquinolone antibiotics.
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