Empirical relationship between chiral selectivity and mobile phase modifier properties

An empirical relationship was derived which relates properties of the mobil e phase modifier to the chiral selectivity factor for a given analyte/chira l selector combination. Using carbon dioxide and heptane-based mobile phase s, the effect of various mobile phase modifiers on Pirkle-type stationary p hases may be accurately modeled using a two-parameter equation. Similar res ults are obtained using cellulosic stationary phases with carbon dioxide-ba sed mobile phases. Modeling separations performed using heptane-based mobil e phases with cellulosic stationary phases were not successful. The predict ive ability of this modeling approach was demonstrated using novel modifier s and chiral analytes. (C) 1999 Dupont Pharmaceuticals Co. Published by Els evier Science B.V. All rights reserved.