Ergot alkaloids as chiral selectors in capillary electrophoresis : determination of the separation mechanism

Recently ergot alkaloids were introduced as novel chiral selectors in capillary electrophoresis. Stereoselectivities of several ergot alkaloids, added to the background electrolyte (BGE), towards some racemic hydroxy org. acids are compared. The 1-allyl deriv. of (5R,8S,10R)-terguride (allyl-TER) proved to be the best chiral selector for these analytes. Only the capillary was filled with BGE contg. the chiral selector. The in- and outlet vial did not contain any ergot alkaloid. The effects of pH, and MeOH added to the BGE were studied. Low pH proved to have an adverse effect on enantiosepn. Good sepn. for the enantiomers of some alpha -hydroxy acids was obtained at pH 4.2, and 25 mM allyl-TER. The addn. of 50% MeOH to the BGE altered stereoselectivity and increased the soly. of the chiral selector. Using a BGE contg. 50% MeOH, and 62.5 mM allyl-TER at pH* 5.5, the optical isomers of all test compds., including tropic acid and other org. acids, were baseline resolved. [on SciFinder (R)]