j. res. pharm. Journal of Research in Pharmacy 2630-6344 Marmara University 10.12991/jrp.2018.94 Pharmaceutical Analytical Chemistry Eczacılıkta Analitik Kimya Investigating the physicochemical properties of phenazopyridine hydrochloride using high-performance liquid chromatography and UV-visible spectrophotometry https://orcid.org/0000-0001-7712-5512 Çelebier Mustafa HACETTEPE UNIVERSITY, FACULTY OF PHARMACY, DEPARTMENT OF BASIC PHARMACEUTICAL SCIENCES, DEPARTMENT OF ANALYTICAL CHEMISTRY https://orcid.org/0000-0002-1076-1300 Koçak Engin HACETTEPE UNIVERSITY, FACULTY OF PHARMACY, DEPARTMENT OF BASIC PHARMACEUTICAL SCIENCES, DEPARTMENT OF ANALYTICAL CHEMISTRY https://orcid.org/0000-0002-5828-4697 Doğan Ayşegül HACETTEPE UNIVERSITY, FACULTY OF PHARMACY, DEPARTMENT OF BASIC PHARMACEUTICAL SCIENCES, DEPARTMENT OF ANALYTICAL CHEMISTRY https://orcid.org/0000-0003-2864-9218 Altınöz Sacide HACETTEPE UNIVERSITY, FACULTY OF PHARMACY, DEPARTMENT OF BASIC PHARMACEUTICAL SCIENCES, DEPARTMENT OF ANALYTICAL CHEMISTRY https://orcid.org/0000-0001-5370-2362 Başcı Akduman Nursabah Elif HACETTEPE UNIVERSITY, FACULTY OF PHARMACY, DEPARTMENT OF BASIC PHARMACEUTICAL SCIENCES, DEPARTMENT OF ANALYTICAL CHEMISTRY 06 27 2025 22 4 528 535 02 27 2018 04 27 2018 Copyright © 2010, Journal of Research in Pharmacy 2010 Journal of Research in Pharmacy

The purpose of this study is to develop high-performance liquid chromatography (HPLC) and ultravioletvisible (UV-Vis) spectrophotometry methods for the determination of pKa, log P, and log D values of phenazopyridine hydrochloride (PHCl). For the HPLC analysis, the pH of the mobile phase was plotted against the capacity factor, and the pKa value was obtained from a sigmoidal relationship. Meanwhile, for the UV-Vis spectrophotometric study, the absorbance of PHCl was plotted against pH at 332 nm to obtain the pKa value. The log P and log D (at pH 2.0) values were then calculated based on the concentration of PHCl in the octanol/water phase. Using the HPLC method, the pKa value was established as 5.05 (± 0.15). Meanwhile, the spectroscopic technique afforded pKa values of 5.20 (± 0.22) and 5.17 (± 0.17) via a classical sigmoidal curve and the Albert and Serjeant method. The log D (at pH 2.0) and log P values of PHCl were 1.61 (± 0.16) and 2.62 (± 0.11), respectively. The obtained results are in good agreement with each other. The pKa, log P, and log D values of PHCl can be determined by HPLC and UV-Vis spectrophotometry with reproducible results.

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