Abstract
The effect of the size of alkyl substituent (ethyl, 2-propyl, 1-butyl or 2-butyl) in the ester group of benzoyl derivatives of amino acids on the separation factor and retention of enantiomers was examined. Pirkle type chiral stationary phase (R)-3,5-dinitrobenzoylphenylglycine) and binary nonaqueous eluents were used. The Snyder-Soczewiński linear equation was applied for presentation of retention vs. eluent composition relationships, which permits the evaluation of separation selectivity in a wide range of concentrations of the more polar component in the binary mobile phase.
It was found that, in the majority of cases, the best separation was obtained for 2-propyl derivatives of amino acids, although some exceptions from this rule were also observed. Similarly, in some cases, the ethyl derivatives of amino acids do not exhibit the strongest retention.
Both selectivity, as well as retention, depended on the type and concentration of the more polar component of the eluent.