Enantiomer separation on monolithic silica HPLC columns using chemically bonded methylated and methylated/acetylated 6-O-tert-butyldimethyl- silylated β-cyclodextrin

Abstract

A new 2,3-methylated 3*-monoacetylated 6-O-tert-butyldimethylsilylated beta-CD derivative was synthesized and chemically bonded onto aminopropyl derivatized monolithic silica HPLC columns. In this CD derivative, only one of seven methyl groups in 3-position was substituted by an acetyl group. Its applicability as a chiral stationary phase for HPLC was tested and compared with exclusively 2,3-methylated 6-O-tert-butyldimethylsilylated beta-CD immobilized onto aminopropyl-modified monoliths. Thirty-two chiral compounds from different chemical classes and different functionalities were tested under RP conditions. Fourteen compounds were resolved into their enantiomers by methylated 6-O-tert-butyldimethylsilylated beta-CD. By use of methylated/acetylated 6-O-tert-butyldimethylsilylated beta-CD as the chiral stationary phase 7 analytes were successfully stereodifferentiated.

Cyano bonded silica monolith—Development of an in situ modification method for analytical scale columns

“…The development of this in situ method was kept as simple, cost and time efficient as possible to produce a chemically bonded analytical sized monolith [2,5,6,14].…”

“…In this study, we illustrate the cyano modification of analytical scale silica rod encased monoliths using a procedure similar to that of Bayer et al [2] and Lubda et al [5,6]. We employed these procedures (with some modifications) as they yielded the highest column efficiencies for analytical scale columns reported in the literature.…”

“…The column efficiency of the modified monolith measured in the number of theoretical plates (N) was less than aminopropylsilica particulate columns. Aminopropyl-silica monoliths were also prepared by Bayer et al [2] and Lubda et al [5], who further modified these monoliths with a cyclodextrin (CD) derivative and used them for enantiomeric separations. The column efficiency for 2-nitroanisole was 73,584 N/m for the column prepared by Bayer et al [2] after amino-propyl derivatisation, but there was no measure of the column efficiency following CD derivatisation.…”

“…Aminopropyl-silica monoliths were also prepared by Bayer et al [2] and Lubda et al [5], who further modified these monoliths with a cyclodextrin (CD) derivative and used them for enantiomeric separations. The column efficiency for 2-nitroanisole was 73,584 N/m for the column prepared by Bayer et al [2] after amino-propyl derivatisation, but there was no measure of the column efficiency following CD derivatisation. The column prepared by Lubda et al [5] showed that the highest N value reached was 36,770 N/m using methadone.…”

“…There are only few studies involving modified analytical scale silica monoliths in the current literature [2][3][4][5][6][7][8][9]. Sutton and Nesterenko prepared an aminopropyl-silica monolith [3], which was then used in normal phase HPLC for the separation of alkyl benzenes, and the sub-fractionation of a complex petroleum fraction.…”