Environmental sustainability assessment of reverse-phase liquid chromatography for retention and ionization profiling of angiotensin-converting enzyme inhibitors.

This paper presents a sustainable chromatographic framework using reverse-phase liquid chromatography (RPLC) method with an ultraviolet detector (UV) to determine the ionization behavior of three angiotensin-converting enzyme (ACE) inhibitors, benazepril, cilazapril, and quinapril, in a water-organic solvent binary mixture. In this study, retention-mobile phase pH data under various hydroorganic conditions were analyzed using nonlinear regression (NLREG) and linear solvation energy relationship (LSER) approaches to calculate the dissociation constant (pKass) values of the compounds. Accurate aqueous pKa (pKaww) values are essential for predicting ionization-dependent solubility, chromatographic behavior, and biopharmaceutical performance of ACE inhibitors. Chromatographic experiments were conducted at 25 °C and 37 °C on a YMC Triart C18 column in ethanol-water, methanol-water, and acetonitrile-water mixtures (40-55% v/v). The pKaww values of the compounds in aqueous medium were calculated using two different temperatures and approaches. At 37 °C, pKa1ww values for cilazapril, benazepril, and quinapril were calculated as 3.715, 3.819, and 3.967, respectively; and pKa2ww values were calculated as 5.316, 5.187, and 5.226, respectively. The values calculated from these studies are compatible with each other and with the literature values. The dependence of the developed methods on twelve green analytical chemistry (GAC) principles was evaluated using the Analytical Greenness Metric (AGREE score=0.77), the Green Analytical Procedure Index (GAPI), and the Analytical Green Star Area (AGSA score=90.28).