![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
The main parameters related to the retention behavior of some oxicam drugs (meloxicam, piroxicam, and tenoxicam) in reversed‐phase liquid chromatography (RP‐LC) processes using a monolithic column were studied under isocratic elution conditions. The hydrophobicity parameter (octanol/water partition coefficient) obtained by extrapolation of the capacity factor—methanol content of the mobile phase relationship did not fit the well‐known dependence on pH. This fact might be assigned to the keto–enolic equilibrium that does not behave like common acids. The dissociation constants for these oxicams were estimated from the retention dependence on the organic modifier content (methanol) in the mobile phase and pH of aqueous components (interval 2–7). Two corrections were applied to the hydrophobicity parameter of analytes, taking into consideration the pH of aqueous component in the mobile phase, and hydrophobicity parameter of the stationary phase. The results were compared to other experimental data and data predicted by the fragment methodology.