Measurement of enantiomeric purity by ratio chromatograms with a photometric detector using quartz plates as a multiple retarder

The measurement of enantiomeric purity is presented using the dual-wavelength detection function of a spectrophotometric detector. Between enantiomers, this method measures the difference in the absorbance ratio at adjacent 1/4 wavelengths that are produced by a thin quartz plate placed on a flow-cell. The use of a split-type flow-cell achieved high sensitivity. Moreover, the determination of absolute quantities of the analyte was successful from the peak shape by adjusting the ratio of effluent velocity between the reference and sample cells to 1/3. This method was applied to the determination of camphor in pharmaceutical preparations.