Chiral separations.

REVIEWS This review covers developments and applications in chiral separations from January 2000 to March 2002. This review is not intended to be a comprehensive review of all papers published, but focuses on major developments in the field of chiral separations as well as representative applications. The review is restricted to the English language literature except as noted for several specific review articles. Several interesting trends were noted in this review as compared to the 2000 Fundamental Review on Chiral Separations (1). While this is primarily anecdotal evidence since an exhaustive comprehensive search was not performed, the trends noted are believed to be indicative of the popularity and general usefulness of the respective chiral stationary phases or chiral separation techniques. Capillary electrophoresis publications decreased by 45% in the 2002 review, with the most significant decrease occurring in cyclodextrin-based separations. The number of publications on capillary electrophoresis using antibiotics, micelles, and miscellaneous chiral selectors remained relatively steady from the 2000 to the 2002 review. While the number of publications on chiral separations in thin-layer chromatography and supercritical fluid chromatography remained relatively steady, the field of enantioseparation in gas chromatography has increased substantially, with an eightfold increase in the number of publications in the 2002 review period. One reason for the increased number of publications in gas chromatography is that, unlike other techniques, many new chiral phases for gas chromatography have been introduced, thus leading to many applications. The number of publications in the field of chiral separations in highperformance liquid chromatography has remained relatively steady, with the exception being a 50% increase in publications using antibiotic-based chiral stationary phases. Separations utilizing capillary electrochromatography also experienced an increase in publications. Capillary Electrophoresis (CE). Capillary electrophoresis remains a popular technique for the enantioseparation of pharmaceutical compounds, with numerous reviews published from January 2000 to March 2002. A review with 264 references summarizing chiral separations of amino acids and peptides by CE using broad classes of chiral selectors, including cyclodextrins (CDs) and their derivatives, antibiotics, and chiral surfactants, and indirect chiral separation utilizing micelles and polymeric pseudostationary phases, as well as derivatization agents for highsensitivity detection was compiled by Wan and Blomberg (2). An overview of the application of CE in chiral separations and various chiral selectors including CDs, chiral micelles, crown ethers, chiral ligands, proteins, oligoand polysaccharides, and macrocyclic antibiotics was described by Amini (3). The theory and application of CE in drug analysis, including chiral separations was summarized in Portuguese (4). Another comprehensive review with 276 references of recent developments in chiral separations by electromigration techniques was published by Gubitz and Schmid (5), with the focus of this review on new chiral selectors, new techniques, and mechanisms of the different chiral separation principles. Charged cyclodextrins as chiral selectors in CE in pharmaceutical analysis were the focus of a review with 157 references (6), and CD use in CE and micellar electrokinetic chromatography was reviewed in Chinese (7). Techniques for the CE enantioresolution of chiral pollutants in the environment were described by Garrison (8), who also discussed advantages, disadvantages, and applications to environmental problems. Rundlett and Armstrong reviewed the methods for the determination of binding constants by CE, including advantages and disadvantages of experimental approaches, for six different CEbased techniques (9). Examples of each method and recent references on its use were given in this review with 50 references. A review surveying the basis theory of direct enantiomeric resolution using chiral selectors in CE was presented (10), in which equations needed for optimization, types of chiral selectors, and recent developments in preparative enantioseparation by continuous free-flow systems and by isoelectric membranes are Anal. Chem. 2002, 74, 2863-2872