Enantioseparation of tartaric acid by ligand-exchange capillary electrophoresis using contactless conductivity detection

A method for the determination of tartaric acid enantiomers using CE with contactless conductivity detection has been developed. Cu(II) as a central metal ion together with l-hydroxyproline were used as a chiral selector, the BGE was composed of 7 mM CuCl2, 14 mM trans-4-hydroxy-l-proline, and 100 mM epsilon-aminocaproic acid; the pH was adjusted to 5 by hydrochloric acid. Separation with a resolution of 1.9 was achieved in 9 min in a polyacrylamide-coated capillary to suppress the EOF. Various counterions of the BGE were studied, and migration order reversal was achieved when switching from epsilon-aminocaproic acid to l-histidine. With detection limits of about 20 M, the method was applied to the analysis of wine and grape samples; only l-tartaric acid was found.