[Methods, developments and applications of circular dichroism and simultaneous dual CD/UV spectroscopy in analytical...

Circular dichroism (CD) is one of the few sensitive indicators of molecular configuration. CD spectroscopy has therefore long been used for structure elucidation. Recent trends show, however, an enormous progress of CD spectroscopy in analytical chemistry, either as an independent method, or as a detector in hyphenated separation techniques. Its uses became especially widespread in pharmaceutical analyses, since enantiomeric purity is a crucial criterion of drug quality. Objectives of the present Ph.D. work included fundamental research in CD and related methodologies, but also, its applications in pharmaceutical analysis. A technical prerequisite of our research work was the instrumental hyphenation of separation and chiroptical detection techniques, which has been achieved by the combination of high performance liquid chromatographic and circular dichroism spectroscopic devices. Our home-built apparatus was the first HPLC-CD instrument in Hungary. Its uses allowed the elaboration of a new method for the determination of peak homogeneity, which applies simultaneous, dual CD/UV detection, and a subsequent ratio-formation. An improved version of this method resulted in the deconvolution of overlapping chromatographic peaks. Another type of peak homogeneity control method was elaborated by rapid, on-line recording of CD spectra in the progress of elution, in order to analyse apparently homogeneous peaks. Circular dichroism has also been applied to quantitate enantiomeric purity in composite samples without any separation of the analytes, and also, to determine equilibrium constants of protonating chiral compounds.