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Green Spectrofluorometric Method for Labetalol Determination Based on Electron Transfer Inhibition With Density
Humood Al Shmrany1, Ali Alqahtani2, Taha Alqahtani2
1Department of Medical Laboratory, College of Applied Medical Sciences, Prince Sattam bin Abdulaziz University, Al-Kharj, Saudi Arabia.
Summary
A new spectrofluorimetric method enhances labetalol hydrochloride detection using photoinduced electron transfer (PET) blocking. This acidification-induced fluorescence method offers sensitive and reliable quantification in pharmaceutical and biological samples.
Area of Science:
- Analytical Chemistry
- Spectroscopy
- Medicinal Chemistry
Background:
- Accurate quantification of labetalol hydrochloride is crucial for therapeutic drug monitoring and quality control.
- Existing analytical methods may involve toxic reagents or lack sensitivity.
- Photoinduced electron transfer (PET) mechanisms offer potential for sensitive fluorescence-based assays.
Purpose of the Study:
- To develop and validate a novel, sensitive, and environmentally sustainable spectrofluorimetric method for labetalol hydrochloride determination.
- To elucidate the underlying photoinduced electron transfer (PET) blocking mechanism using quantum mechanical calculations.
- To optimize the method using D-optimal experimental design and validate it according to ICH guidelines.
Main Methods:
- Spectrofluorimetric analysis utilizing acidification-induced fluorescence enhancement.
- Quantum mechanical calculations to investigate the PET mechanism and electronic structure changes.
- D-optimal experimental design for systematic optimization of reaction conditions.
- Validation according to International Council for Harmonisation (ICH) guidelines.
Main Results:
- A five-fold fluorescence enhancement of labetalol hydrochloride was achieved at 415 nm upon excitation at 298 nm due to protonation-induced PET blocking.
- Quantum mechanical calculations confirmed protonation stabilizes the HOMO level and reduces electron density, quenching the PET mechanism.
- Optimized conditions included 0.6-M acetic acid, 5-min incubation, and a water-ethanol mixture.
- The method demonstrated excellent linearity (10-300 ng/mL), a low detection limit (3.23 ng/mL), and high precision (<1.6% RSD).
- Successful application to pharmaceutical formulations and plasma samples showed high recovery rates (96.36%-104.97%).
Conclusions:
- The developed spectrofluorimetric method based on PET blocking is sensitive, reliable, and suitable for labetalol hydrochloride determination.
- This approach offers an environmentally friendly alternative, avoiding toxic derivatization reagents.
- The method's successful validation and application highlight its potential for routine analysis in quality control and biological sample analysis.