Determination of protonation constant value of thiabendazole in ethanol-water binary mixtures by green RPLC method

Abstract

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 ( 𝑝𝐾 ! " ") values of thiabendazole in 15, 20, 25, and 30% (v/v) ethanol-water binary mixtures at 37 o C 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 # $ 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 𝑝𝐾 ! " " value and the macroscopic properties of ethanol was investigated. Compatibility was observed between the pKa ( 𝑝𝐾 ! % %) values in the aqueous medium determined by this linear approach. By using the 𝑝𝐾 ! % % value calculated for thiabendazole, the ionization percentages were calculated at different pH (1-12) values with the Henderson-Hasselbalch equation.