SEPARATION OF CHARGED AND NEUTRAL ISOTOPIC MOLECULES BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY IN COATED CAPILLARIES

Some unique separations are reported of pairs of deuterated and non-deuterated compounds by capillary zone electrophoresis (CZE) in coated capillaries in the absence and presence of surfactant micelles. Pyridine (pyridine-h(5)) and [H-2(5)]pyridine (pyridine-d(5)) could be separated in plain buffer (R = 1.1) and in 2% Nonidet P-40 (R = 1.5). Owing to the good separation obtained, it was possible to assess the degree of cross-contamination when ''pure'' isotopes were analysed. A 1:1 mixture of benzoic-h(5) and -d(5) acid was poorly separated in the absence of detergent (R = 0.39) but well separated in 50 mM sodium dodecyl sulphate (SDS) (R = 1.14). Benzyl-h(5) and -d(5) alcohol were reasonably well separated in a micellar system containing 50 mM SDS (R = 1.02) (a separation previously unreported in the literature). Benzene-h(6) and -d(6) were well separated again in presence of 50 mM SDS (R = 1.59). It appears that CZE offers a unique environment for the separation of positively and negatively charged and neutral isotope mixtures, previously reported only using RP-HPLC and GC.