¹Department of of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Süleyman Demirel University, Isparta, Turkey
²Department of Pharmaceutical Research and Development, Faculty of Pharmacy, Süleyman Demirel University, Isparta, Turkey DOI : 10.29228/jrp.670 In this study, an environmentally friendly analysis of an anti-infective/anthelmintic drug thiabendazole was carried out by liquid chromatography method using ethanol solvent that is not harmful to human health and the environment. Protonation constant (^s_sPK_a ) values of thiabendazole in 15, 20, 25, and 30% (v/v) ethanol-water binary mixtures at 37 oC were obtained by using the green reverse phase liquid chromatography method. The method is based on a model that relates the chromatographic behavior of the determined analytes to pH. The linear relationship between the solvatochromic parameter E^N_T and the retention values of the compound was determined depending on the variation of the organic solvent in the mobile phase. The relationship between the calculated ^s_sPK_a value and the macroscopic properties of ethanol was investigated. Compatibility was observed between the PK_a (^w_wPK_a ) values in the aqueous medium determined by this linear approach. By using the ^w_wPK_a value calculated for thiabendazole, the ionization percentages were calculated at different pH (1-12) values with the Henderson-Hasselbalch equation. Keywords : Benzimidazole; pK_a value; ethanol-water mixtures; modeling of retention