Development of a variable-wavelength optical rotation detector in the ultraviolet region.

A new type of optical rotation (OR) detector based on the phase retardation of the first-order diffraction beam has been constructed. The proposed detector responded to only OR properties by eliminating the circular dichroism (CD) effect. Thus, it could measure the optical rotatory dispersion curves in the Cotton band. Although the optical system requires the incident beam in which the phase retardation is 0.5π, the actual retardation was estimated to be around 0.3π. It means that the OR signal intensity can be doubled. Since the proposed detector works over a range of UV wavelengths, there was a compound whose OR signal intensity was higher than the CD signal intensity. The OR detection was superior to CD in stability and in defining the baseline.