Application of UV spectrophotometry and reversed-phase HPLC to determine the ionization constant of a new biologically active compound

Abstract

Aim to determine the ionization constant (pKa) of the biologically active compound 2-ABPPC by UV spectrophotometry and high performance liquid chromatography (HPLC). Material and methods. The object of the study was the substance 2-ABPPC (2-amino-1-(4-bromophenyl)-5-(3,3-dimethyl-2-oxobutylidene)-4-oxo-4,5-dihydro-1H-pyrrole-3- carboxamide). The methods of UV spectrophotometry and high performance liquid chromatography were used to determine the ionization constant. The spectrophotometric analysis was carried out on a Shimadzu UV-1800 spectrophotometer. The chromatographic determination of the pKa value was carried out on an LC-20 Prominence liquid chromatograph (Shimadzu) using a Zorbax Extend-C18 reversed-phase column. Results. In the course of study, it was found that 2-ABPPC has one pKa value. When using two different methods to estimate the ionization constant, the comparable results were obtained: 7.64 (UV spectrophotometry method) and 7.40 (reversed phase HPLC method).