Non‐specific retention characteristics of dissolved β‐cyclodextrin derivatives in open tubular column gas chromatography

Abstract

Non-specific retention characteristics of dissolved b-cyclodextrin derivatives in open tubular column gas chromatographyThe solvation parameter model is used to identify contributions from intermolecular interactions responsible for non-specific retention in gas chromatography for three dissolved b-cyclodextrin derivatives in a poly(cyanopropylphenyldimethylsiloxane) stationary phase. The cyclodextrins are permethylated b-cyclodextrin (Cyclodex-B), heptakis(2,3-di-O-methyl-6-O-t-butyldimethylsilyl)-b-cyclodextrin (CycloSil-B) and heptakis(2,3-di-O-acetoxy-6-O-t-butyldimethylsilyl)-b-cyclodextrin (Rt-bDEXsa). Taking DB-1701 as a reference phase for the poly(cyanopropylphenyldimethylsiloxane) solvent, it is shown that the dominant interactions for the cyclodextrin derivatives are associated with their hydrogen-bond basicity and capacity for dipole-type interactions. None of the cyclodextrin derivatives are hydrogen-bond acids and all are weakly electron lone pair repulsive. The cohesive properties of the dissolved phases are similar to those of the solvent, except for Rt-bDEXsa, which is significantly more cohesive. Also, Rt-bDEXsa shows significant inclusion complexation for the compounds used to determine the system constants of the solvation parameter model resulting in poor statistical models, suitable only for qualitative interpretation. The Cyclodex-B and CycloSil-B columns are compared to a database of 23 open-tubular column stationary phases possessing similar selectivity to each other but different selectivity for non-specific interactions to the other stationary phase types.

Separation characteristics of phenyl-containing stationary phases for gas chromatography based on silarylene-siloxane copolymer chemistries

“…Sample volumes of 2 lL were introduced by split injection (split vent flow rate 10 mL/min and septum purge 5 mL/min), at an injection temperature of 2408C. Measurements of the retention factor (log k) were made isothermally at 60, 80, 100, 120, and 1408C by injecting compounds individually [10,17,18].…”

Enantioseparation of agrochemicals by gas chromatography. Exploring columns based on cyclodextrin derivatives dissolved into polysiloxanes

“…Enantiomeric analysis can be performed by different analytical techniques [5][6][7][8][9][10][11]. A comprehensive compilation and classification of chiral agrochemicals according to their primarily used, [12], gathered information on enantioseparation methods for those agrochemicals by liquid chromatography (LC), gas chromatography (GC), and capillary electrophoresis (CE).…”

Assessment of the selectivity equivalence of DB‐608 and DB‐624 open‐tubular columns for gas chromatography

“…The system constants are determined at 208C intervals over the temperature range 60 to 1408C using a standard protocol. Interrogation of the database allowed the identification of quantitative relationships between stationary phase composition and chromatographic selectivity [2 -5]; the identification of redundant stationary phases with different compositions but similar selectivity [5,6]; confirmation of the equivalent selectivity of nominally identical stationary phases from different sources [7 -9]; and assessment of the non-specific interactions of dissolved cyclodextrins [10]. In these studies stationary phases of known structure were used to allow interpretation of the results in terms of changes in stationary phase composition.…”