Separation of positional isomers on A,C- and A,D-bridged calix[6]arene as stationary phases in capillary GC

A,C-Bridged (ACCX) and AP-bridged isopropyldimethylsilylcalix[6]arene (ADCX ) dissolved in OV-1701 were used as stationary phases in isothermal capilla ry gas chromatographic separation of some positional isomers. Retention fac tors and separation factors for the isomers were measured. The isomers inve stigated are well resolved on the two phases. Retention of all the solutes investigated is longer on ACCX than on ADCX, The longer retention on A,C-br idged calix[6]arene is probably due to extra inductive interactions of the solute molecule with the carbonyl moieties in the phase. Separation factors for closely eluting isomer pairs are similar on the two phases. This seems to indicate that the carbonyl moieties do not play an appreciable role in discriminating the isomer molecules on entering the cavity of the calixaren e if the solute is retained by the inclusion process.