SOLVATOCHROMIC STUDIES ON REVERSED-PHASE LIQUID-CHROMATOGRAPHIC PHASES .2. CHARACTERIZATION OF STATIONARY AND MOBILE PHASES

UV-visible spectra of three solvatochromic dyes, chloro-2-[2-(1-methyl -4-pyridinio)vinyl]phenolate, N-methyl-2-nitroaniline, and 2-nitroanil ine, are employed to characterize the octadecyl-derivatized silica (OD S2) stationary phase and the corresponding mobile phases used in rever sed-phase liquid chromatography. The mobile phases studied are methano l-water, acetonitrile-water, and tetrahydrofuran-water, with compositi on ranges from 100% to 5% of organic modifier. Across the whole mobile phase composition range, the ODS2 stationary phase shows three distin ct behaviors upon variation of the mobile phase composition, which are described as non-retentive, solvated, and collapsed.