Retention behavior and mechanism of adsorption of some chloropyridine isomers in normal phase liquid chromatography on silica, cyano-silica and amino-silica columns

Abstract

The retention behaviour of some chloropyridine isomers on silica, cyano-silica and amino-silica columns in normal phase liquid chromatography has been studied. Retention times on first two columns follow similar pattern while is different on amino-silica column. An equation for inter comparison of columns for selectivity purpose is developed and verified. Log <i>k' versus </i>log <i>X</i>_B plots follow Snyder and Soczewinski model of adsorption. A mixed interaction of involving hydrogen bonding and dipolar interactions are responsible for the retention of solutes on silica and cyano-silica columns and weak hydrogen bonding interaction lead to separation on amino-silica column. Cyano-silica column is preferred for their separation considering the retention times. However, best selectivity is seen for monoisomers and 2,6-DCP on either silica or cyanosilica column and 3,5-DCP and 2,3,5-TCP on amino-silica column.