Send Orders for Reprints to reprints@benthamscience.net Current Chromatography, 2014, 1, 81-89 81 Recent Trends in Chiral Separations by Nano Liquid Chromatography and Nano Capillary Electrophoresis Imran Ali 1, *, Zeid A. Al-Othman 2 , Abdulrahman Al-Warthan 2 and Hassan Y. Aboul-Enein 3 1 Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi-110025, India; 2 Department of Chem- istry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia; 3 Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Cairo 12311, Egypt Abstract: Chiral separation at nano scale is gaining importance in drugs development, proteomic, genomic and environ- mental sciences. Generally, traces of drugs are found in our body for several weeks. These cannot be detected by conven- tional analytical techniques. The present article discusses the advances in chiral resolution at nano scale using nano liquid chromatography (NLC) and nano capillary electrophoresis (NCE). The instrumentation, chiral selectors, mechanisms of chiral recognition and future challenges and prospectives have been discussed. Keywords: Chiral separations, nano liquid chromatography (NLC), nano capillary electrophoresis (NCE), chiral recognition mechanisms, Challenges and prospectives. 1. INTRODUCTION The concept of chirality is related with work of Haüy in 1809 [1] and Pasteur [2]. In the present century, chirality is gaining importance in various fields such as pharma- ceuticals, agrochemical and other chemical industries. Be- sides, the importance of chirality is also realized by envi- ronmental scientists [3]. It is well known that one of the enantiomers is pharmacologically active while the other may be inactive or ballast or toxic; leading to various side effects and toxicities [4, 5]. US-FDA, Health Canada, Pharmaceuti- cal European Committee for Proprietary Medicinal Products and Medical Devices Agencies of Japan, have banned the selling of racemic drugs [6-8]. The enantiomeric differences at superamolecular level are due to stereoselective drugs binding, clearance, absorption, metabolism and excretion. The interactions mainly occurred with different human plasma proteins [9]. It is interesting to note that some opti- cally active pure drugs racemize resulting into toxicity. (+)- Thalidomide racemises into harmful (-)-antipode both in vitro and in vivo leading to teratogenic effect on embryo of pregnant women [10, 11]. Besides, chiralty plays a crucial role in drug design and development for some other drugs [3,12,13]. The importance of chirality has been realized in environmental pollutants, fragrances, and flavors. There are many methods for the separation and identifi- cation of chiral molecules. The most important are various modalities of chromatography and electrophoresis [12]. Re- cently, it has been realized that drugs remain in our body for long time at trace levels of nano and pico gram levels. Be- sides, chiral pollutants are also present at these trace concen- *Address correspondence to this author at the Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi-110025, India; Tel: +9211458226; Fax: 0091-11-26985507; E-mails: drimran_ali@yahoo.com; drimran.chiral@gmail.com trations. The presence of unwanted enantiomers in the body and environment is not desirable. During the course of time, the chiral identities at trace levels accumulate into the body and environment leading to various side effects and diseases. Proteomics and genomics are recent areas of research and, therefore, need analytical methods with detection limits at nano or lower level. In view of these facts, it is important to explore the analytical methods capable to distinguish stereoi- somers at nano or low level detection limits. Recently, two techniques i.e. nano liquid chromatography (NLC) and nano capillary electrophoresis (NCE) have emerged [14]. These methods require small amount of sample and mobile phase with low limits of detections such as nano or pico grams. Some work has been carried out on chiral separation using these techniques which are gaining importance in chiral analyses nowadays. Keeping in view the importance of chiral analyses with low limits of detections, efforts are made to review the separation and identification of chiral resolution by NLC and NCE methods. 2. INSTRUMENTATION Basically, the main component of NLC and CE is micro chip and, hence, also called as micro chip chromatography and electrophoresis. The readers interested in detailed infor- mation on micro chips should consult our book on this sub- ject [14]. The micro chips are made of glass, quartz or other polymeric materials. Micro channels are engraved on these chips, which contain chiral selectors. The separation occurs in a channel due to the competition between the analytes and the chiral selectors. NLC and NCE instruments work as normal chromatographic and electrophoretic modalities. The sample is loaded by a second channel; perpendicular to the separation channel. Generally, length, width and depth of the channels vary from 30-40 mm, 40-50 m and 15-17 m, respectively. The diagrammatic representation of NLC and NCEC are shown in (Figs. 1 and 2), respectively. 2213-2414/14 $58.00+.00 © 2014 Bentham Science Publishers