Coupled achiral-chiral HPLC

The determination of the enantiomers of mefloquine in plasma and whole blood using a coupled achiral-chiral HPLC system" (38). A... 

In HPLC, the direct serial coupling of achiral and chiral columns for the simultaneous achiral/chiral separation of a range of components in a complex mixture was not feasible due to either the increased backpressure or the different mobile-phase requirement. However, this concept is not restricted for SFC because the supercritical fluid not only has a significantly lower viscosity than a liquid but is also an effective eluent for both chiral and achiral stationary phases [52], As an example, an SFC-MS approach using the coupled achiral/chiral column combination was reported to significantly enhance the separation efficiency for the reaction mixtures of cinna-monitrile and hydrocinnamonitrile intermediates to determine the diastereometric/ enantiometric composition of the final product in one step [52], Characterization of... 

He, J., Shibukawa, A., Nakagawa, T., Wada, H., Fujima, H., Imai, E., Go-oh, Y. (1993). Direct injection analysis of atenolol enantiomers in plasma using an achiral/chiral coupled column HPLC system. Chem. Pharm. Bull. 41, 544—548. 

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