HPLC enantioseparation of β2-homoamino acids using crown ether-based chiral stationary phase

RP high-performance liquid chromatographic methods were developed for the enantioseparation of eleven unusual beta(2)-homoamino acids. The underivatized analytes were separated on a chiral stationary phase containing (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as chiral selector. The effects of organic (alcoholic) and acidic modifiers, the mobile phase composition and temperature on the separation were investigated. The structures of the substituents in the alpha-position of the analytes substantially influenced the retention and resolution. The elution sequence was determined in some cases: the S enantiomers eluted before the R enantiomers.