Influence of the concentration of adsorbate and modifier in the mobile phase on retention in high-performance liquid chromatography

Chromatographic separation of phenylpropanol enantiomers on a quinidine carbamate-type chiral stationary phase

The retention and the separation of the enantiomers of 1-phenylpropanol (1PP), 2-phenylpropanol (2PP), and 3-chloro-1-phenylpropanol (3CPP) on silica-bonded quinidine carbamate under normal phase HPLC conditions were investigated. A relatively high selectivity of the stationary phase for 3CPP and 1PP (alpha approximately 1.07-1.09) was achieved with eluents containing ethyl acetate as the polar modifier. These mobile phases were examined in detail. Based on the set of chromatographic and thermodynamic data collected, conclusions regarding the mechanism of enantioselectivity and the structure of the selector chiral center are made.

Reproducibility of the separation of astaxanthin stereoisomers on Pirkle covalent L-leucine and D-phenylglycine columns

The reproducibility of the separation of astaxanthin stereoisomers on columns packed with Pirkle covalent L-leucine chiral stationary phase (CSP) was examined by comparing six columns purchased from the same manufacturer. Differences were found even for columns packed with CSP from the same lot. The reproducibility of columns packed with Pirkle covalent D-phenylglycine CSP was also examined by comparing columns purchased from the same manufacturer as well as from different manufacturers. Significant differences were found for columns packed by different manufacturers. Chiral column-to-column reproducibility for complex stereoisomeric separations should therefore not be taken for granted.