Development of Chiral Separation Systems for Capillary Electrophoresis, Electrochromatography and Liquid Chromatography

Since the turn of the twentieth century, it has been recognized that many drugs, agrochemicals, food additives and fragrances are chiral compounds and their chirality may considerably affect their bioactive behavior [1, 2]. The demand has been increasing for new analytical methods with high selectivity and efficiency. Chiral separation has become an attractive and important field in the separation sciences. Chromatographic techniques, such as thin–layer chromatography (TLC), gas chromatography (GC), supercritical fluid chromatography (SFC) and high performance liquid chromatography (HPLC), have often been used [3,4], and are conventional techniques for chiral separation. In recent decades great attention has been paid to new separation techniques, such as capillary electrophoresis (CE), capillary electrochromatography (CEC) and microcolumn–liquid chromatography (μ–LC). CE is an analytical technique with a wide range of applications in, for example, the pharmaceutical, biological, and environmental analysis fields. The diverse separation modes make the CE technique a very important tool for chiral analysis. The most frequently applied CE modes for chiral separation are capillary zone electrophoresis (CZE), with the addition of a chiral selector to the background electrolyte (BGE), electrokinetic capillary chromatography (EKC), using chiral pseudo–stationary phases or charged chiral selectors, capillary gel electrophoresis (CGE), with chiral selectors incorporated in gels, and CEC, which employs capillary columns coated with chiral stationary phase (CSP) on the inner wall of capillary, and either packed with CSP or fabricated by monolithic methods. The development of new column technologies, separation modes and molecular recognition materials promotes the development of the chromatographic sciences. This paper provides a brief review of recent advances in the development of chiral separation techniques achieved in the author’s group. The topics include ligand exchange–capillary electrophoresis (LE–CE), ligand exchange–micellar electrokinetic chromatography (LE–MEKC), chiral monolithic silica columns and their applications in CEC and μ–LC, EKC using 18–crown–6– Focusing Review