Electrophoresis 2013, 00, 1–10 1 Alain Wuethrich Paul R. Haddad Joselito P. Quirino Australian Centre for Research on Separation Science (ACROSS), School of Chemistry, University of Tasmania, Hobart, Australia Received August 8, 2013 Revised October 6, 2013 Accepted October 7, 2013 Review Chiral capillary electromigration techniques—mass spectrometry—hope and promise Analytical methods for chiral compounds require a separation step prior to mass spec- trometric detection. CE can separate enantiomers by the use of a chiral selector and can be hyphenated with MS. The chiral selector can be either embedded inside the capillary (electrochromatography) or added into the background solution (EKC). This review de- scribes the fundamentals and highlights the recent developments (September 2009–May 2013) of chiral CEC and EKC with detection using MS. There were 20 research and more than 30 review papers during this period. The research efforts were driven by fundamen- tal studies, such as the development of novel chiral selectors in electrochromatography and of advanced partial filling techniques in EKC in order to optimise separation. Other developments were in application studies, such as in food analytics and metabolomics. Keywords: CEC / Chiral / EKC / MS DOI 10.1002/elps.201300377 1 Introduction The advantages of combining column separation and MS detection which provides structural information (masses or mass fragments) have been demonstrated in various fields, such as in the environmental, pharmaceutical, pharmacolog- ical and toxicological sciences. These approaches are popu- larly known as hyphenated techniques and represent power- ful tools for chiral analysis. Chiral compounds are important in a wide variety of fields, such as drugs, natural products (including toxins), pesticides and biological compounds such as amino acids. Because enantiomers have the same molec- ular weight, their separation is essential prior to MS detec- tion. Thus, the hyphenation of separation and MS methods for analysis of enantiomers had attracted analytical chemists and papers dealing with chiral separation with MS were pub- lished as noted by Schug and Lindner [1]. Separation of enan- tiomers is usually achieved by chromatography, CE, or other electroseparation techniques. During the last few years, the major techniques employed for enantioseparations have been LC and GC. For this rea- son, hyphenated approaches such as LC-MS and GC-MS may be considered as mature techniques. However, the superior Correspondence: Dr. Joselito P. Quirino, Australian Centre for Research on Separation Science (ACROSS), School of Chem- istry, University of Tasmania, Private Bag 75, Hobart, TAS 7001, Australia E-mail: joselito.quirino@utas.edu.au Fax: +61-3-6226-2858 Abbreviations: APPI, atmospheric pressure photo ionisation; DOPA, 3,4-dihydroxyphenylalanine; k, retention factor; poly- L,L-SULV, poly sodium N-undecenoyl-L,L-leucylvalinate analysis characteristics provided by the hyphenation of capil- lary electroseparation methods with MS have not yet been de- veloped to their full extent. CE also has low running costs and minimal sample/reagent requirements. The development of chiral electroseparations coupled with MS was facilitated by the introduction of ESI to interface CE with MS [2]. Most chi- ral CE-MS with ESI has employed a sheath liquid, although sheathless ESI providing better sensitivity is also available. The sheath liquid is prepared using only volatile compounds. The main reason for using a sheath liquid has been to com- pensate for the very low liquid flow from the capillary that does not typically provide a stable electrospray. The pH of the sheath liquid can also be adjusted to facilitate ionisation of weakly acidic or basic analytes. Electroseparation modes that are commonly coupled to MS for chiral analysis are CEC and EKC. In CEC, the chi- ral selector is immobilised and part of the stationary phase. In EKC, enantiomeric separation is achieved by adding the chiral selector to the separation electrolyte. When surfactant or polymer/molecular micelles are used, this mode of EKC is called micellar EKC or MEKC. In both CEC and EKC, the separation principle is based on the differential binding of the compounds in the chiral mixture to a chiral phase or selector. However, conventional CE can also be used after derivatisa- tion of analytes to form diastereomers. The separation prin- ciple in CE is based on differences in the electrophoretic mobilities of the analytes, which for chiral compounds can be introduced by addition of a structural moiety at different positions in the chiral centre. Colour Online: See the article online to view Fig. 1 in colour. C  2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.electrophoresis-journal.com