The Thai Journal of Pharmaceutical Sciences


Background: New specific and sensitive spectrofluorimetric fluorotag method has been developed and validated for the quantification of metformin hydrochloride. Materials and Methods: The derivatization reaction was carried out using 1,2-naphthoquinone-4-sulfonic sulfonate as (NQS) fluorotag in the presence of strong alkaline medium (potassium hydroxide) to form the highly fluorescent product. The fluorescence was observed at emission wavelength 453 nm after excitation at 359 nm. The different experimental conditions affecting the reaction product formation and stability were carefully studied and optimized as 2% w/v of potassium hydroxide solution, 0.5% w/v NQS reagent. Results: At optimum reaction conditions, good linear relationship was found and Beer’s law range was found to between 5 and 30 μg/mL, (R² = 0.999). As per International Conference on Harmonization guidelines, the validation parameters were satisfied (%relative standard deviation <2.0) for accuracy and precision studies. Limit of detection and limit of quantification for proposed method were found to be 0.54 μg/mL and 1.6 μg/mL, respectively. Conclusion: The contemplated method was successfully employed for quantification of metformin in pharmaceutical dosage form, spiked human plasma and urine samples.


Faculty of Pharmaceutical Sciences, Chulalongkorn University

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