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

The retention behaviour of some chloropyridine isomers on silica, cyano-sil ica 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 c olumns for selectivity purpose is developed and verified. Log, k' versus lo g X-B plots follow Snyder and Soczewinski model of adsorption. A mixed inte raction of involving hydrogen bonding and dipolar interactions are responsi ble for the retention of solutes on silica and cyano-silica columns and wea k hydrogen bonding interaction lead to separation on amino-silica column. C yano-silica column is preferred for their separation considering the retent ion 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-sil ica column.