Enantiomer Separation of D-L Branched Amino Acids by Capillary Electrophoresis in Sport Nutritional Supplements

A capillary electrophoresis method was developed for the chiral separation of D-L valine, isoleucine, and leucine. The separation of derivatized amino acids with 9-fluorenylmethyl-chloroformate was performed by micellar electrokinetic capillary chromatography. We optimized the method by varying β-cyclodextrin and sodium dodecyl sulphate concentrations in the presence of 2-propanol. The proposed method was applied to the determination of D-forms of valine, Isoleucine, and leucine in the presence of an excess of relative L forms, in commercial supplements for sport nutrition. Results demonstrated that the separation of enantiomers was possible up to an enantiomeric ratio of 1:100. The analysis of selected products confirmed the enantiomeric purity of utilized amino acids.