Abstract
A circular dichroism (CD) detector based on laser four-wave mixing (FWM) is demonstrated using separate injections of analyte enantiomers onto a standard silica-based microbore high-performance liquid chromatography (HPLC) column. Using the chiral column, a preliminary "detected" mass detection limit of 180 pg is determined inside a laser probe volume of 200 pL, corresponding to a circular dichroism detection limit, DeltaA, of 2.2 x 10(-5) for (-) camphorquinone. Detection sensitivity levels are dramatically improved when our FWM-CD detector is interfaced to a microbore system due to the lower mobile-phase flow rates and the smaller sample concentrations required for the analysis. Using the microbore column, a preliminary circular dichroism detection limit, DeltaA, of 1.6 x 10(-6) and a preliminary concentration detection limit of 4.1 x 10(-4) M are determined for camphorquinone. This corresponds to a "detected" mass detection limit of 33 pg for the chiral compound. Laser wave mixing offers better detection limits than conventional circular dichroism detection methods and, hence, offers many promising applications.
Published Version
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