Enantiomeric separation of selenoaminoacid derivatives by cyclodextrin-modified micellar electrokinetic chromatography using a mixed micellar system of sodium dodecyl sulphate and taurodeoxycholic acid

A new cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC ) method for the enantiomeric separation and determination of the selenoami noacids selenomethionine and selenoethionine, derivatised with 2,3-naphthal enedicarboxaldehyde (NDA) to produce cyanobenzoisoindole (CBI) derivatives, has been developed. Optical resolution was achieved in a fused-silica capi llary column using 30 mmol l(-1) phosphate/10 mmol l(-1) boric acid (pH 7) electrophoretic buffer containing a mixed micellar system of achiral sodium dodecyl sulphate and chiral taurodeoxycholic acid surfactants among with p -cyclodextrins. Detection was followed by direct UV absorptiometric measure ments at 230 nm. The concentration influence of the two chiral selectors us ed (beta-CD and TDC micelles), the effect of applied voltage and the pH of the electrophoretic buffer on the migration time and resolution have been i nvestigated. The analytical performance of the method is discussed in terms of detection limits, linearity of response and precision. The method devel oped has been applied to the determination of enantiomeric purity in a comm ercial sample sold as 'pure' L-selenomethionine. (C) 2000 Elsevier Science B.V. All rights reserved.