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Hold‐up volume and its application in estimating effective phase ratio and thermodynamic parameters on a polysaccharide‐coated chiral stationary phase
Author(s) -
Lao Wenjian,
Gan Jay
Publication year - 2007
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200700213
Subject(s) - chemistry , phase (matter) , surface area to volume ratio , chromatography , enthalpy , volume (thermodynamics) , enantiomer , reproducibility , analytical chemistry (journal) , thermodynamics , organic chemistry , physics
As an “unretained” marker, 1,3,5‐tri‐ tert ‐butylbenzene (TTBB) has been commonly used to measure the hold‐up volume. Despite many racemates have been resolved on Chiralcel OJ column, the hold‐up volume of the column is still not well characterized. The aim of this work was to evaluate the chromatographic behavior of TTBB on the OJ column, and its application in estimating the effective phase ratio and thermodynamic parameters. The hold‐up volume was affected not only by the mobile phase composition but also the solvents used for dissolving TTBB. A higher concentration of TTBB (0.500 mg/mL) showed a better reproducibility than when used at a lower concentration. After correction for thermal expansion of the mobile phase, TTBB was found to have slight retention on the OJ phase. The effective phase ratio increased with an increase in the temperature and decrease in the strength of the mobile phase. The enthalpy and entropy of enantiomers of imidazolinone herbicides were independent of the temperature in a linear van't Hoff plot when the effective phase ratio was changed. This study shows that, based on the hold‐up volume from TTBB, thermodynamic evaluation with parameters derived from the distribution constant is valuable for understanding chromatographic retention and enantioseparation mechanisms of chiral analytes.