The characteristics of a mixed stationary phase containing Permethylated-β-CD and Perpentylated-β-CD in gas chromatography

Permethylated-β-CD (Column A), Perpentylated-β-CD (Column B) and their mixture (Column AB) were investigated in fused-silica capillary gas chromatography (GC). Their polarities and chromatographic properties were studied. They were mixed with OV-1701 to improve their film-formabilities. The concentration of OV-1701 was same in three stationary phases, with the ratio of stationary phase to OV-1701 kept as 20% consistently. The samples including aromatic positional isomers and chiral compounds, such as dl-valine, dl-alanine, (±) indanol, (±) dihydrocarvyl acetate were separated. The results are as followering: (1) the three stationary phases are all moderate polar materials, the averages of permethylated-β-CD, perpentylated-β-CD and their mixture were 859, 816 and 825, respectively. (2) The better separation effect was observed on mixed stationary phase. For example, the separation factor (α) of (±) indanol, dl-alanine, dl-valine and (±) dihydrocarvyl acetate measured on the mixed stationary phases (Column AB) were greater than those obtained on Columns A and B containing single cyclodextrin derivative phases. The α value of dl-valine on the mixed stationary phase is 1.04, which is greater than 1.02, which was obtained on Columns A and B. As for (±) dihydrocarvyl acetate, the α value on Column AB is 1.05. It was also found that cresol (o, m, p), nitrochlorobenzene (m, o), dichlorobenzene (m, p) and cyclohexane/hexane were better separated on Column AB than on Column A or B. These results indicate that the mixed stationary phase had excellent selectivity and good separation ability for some chiral and positional isomers compounds.