CHIROPTICAL DETECTION DURING LIQUID-CHROMATOGRAPHY .3. NONSTOP ACQUISITION OF CIRCULAR-DICHROISM SPECTRA DURING LIQUID-CHROMATOGRAPHY

A new type of spectrometer, built in-house, served as a circular dichroism detector for liquid chromatography. It acquired differential absorbances DELTA-A = f(lambda) at all wavelengths, lambda, between 208 and 268 nm simultaneously within a time interval of 9 s. Non-stop acquisition of circular dichroism spectra during liquid chromatography is described for the first time. The novel set-up gives automatic access to dichrograms without preparative enrichment of enantiomers, if some analytical separation on an optically active sorbent can be achieved. Like photodiode-array detection, the new technique collects ultraviolet spectra A = f(lambda), but furnishes positive/negative information DELTA-A = f(lambda) in addition. It was applied to (+/-)-2,2'-spirobi[2H-chromene] as a test sample and microcrystalline tribenzoylcellulose as a sorbent. Future applications of non-stop liquid chromatographic circular dichroic-ultraviolet data are discussed.