Development and Applications of Chiral Separations and Detection

Chiral separations and detection have increasing become an important subject in science and technology. The popularity stems from the differences in the physiological and therapeutic effects of enantiomeric forms of many compounds. Very often, only one form of the enantiomers is pharmacologically active, while the other or others can reverse or limit the effect of the appropriate enantiomer. Hence the pharmaceutical industry needs effective chiral separation and detection methods. It is our primary goal in this research project to develop the universal and sensitive HPLC detector and discover the new chiral separation media to facilitate the separation and detection of the chiral substances. Tue first part of our research focused on the development of HPLC detector based on the infrared thermal lens spectrometry. This detector is truly universal since it can use the thermal lens technique for either direct or indirect detection. The sensitivity of this detector is high and at least 10 times more than those of the conventional absorption detectors. A detection limit of picograms was achieved for phenol and its chlorinated substances. The second part of our research devoted to incorporate vibrational circular dichroism (VCD) into HPLC detection and develop a universal chiral detector based on the novel instrumentation design. This VCD chiral detector can provide the chirality of optical active compounds in addition to its wide applicability, high sensitivity and selectivity. Micrograms of 2,2,2-trifluoro-(9-anthryl)ethanol and benzoin can be chirally detected by this detector when those compounds were separated from the corresponding racemic mixture by a chiral column. The last part of our research has focused on the isolation and characterization of a new class of macrocyclic oligosaccharides--Cyclooligoarabinofuranoses. Unbranched, mono- and di-branched compounds with their macrocyclic structure formed by (1--5) linkage of either six, seven, eight or nine a.-L-arabinofuranose residues have been isolated and characterized. Their applications have been tested by adding them to buffer to facilitate the separations in capillary electrophoresis