Enantiomeric separation of 1-phenylethylamine and 1-cyclohexylethylamine in capillary electrophoresis with contactless conductivity detection

Contactless conductivity detection was employed for the detection of the enantiomers of 1-phenylethylamine and 1-cyclohexylethylamine which were separated in capillary electrophoresis with unprecedented high resolutions Rs of 2.3 and 3.3, respectively, by using a combination of dimethyl-β-cyclodextrin and the chiral crown ether 18C6H4 as chiral selectors in a citric acid buffer of pH 2.4. The conductivity measurement enabled the direct detection, i.e. without having to derivatize or resort to indirect methods, of all species including the non-UV-absorbing enantiomers of cyclohexylamine. Detection limits of 0.5 μM were achieved and the determination of enantiomeric ratios of up to 99:1 was found possible.