CD Measurement of alanine powder using DRCD method with multiprobe function

Generally, a sample for CD measurement needs to be a liquid (solution) sample, while recently there has been increasing requirements of CD measurement for hardly soluble sample or the sample whose structure may change in a solution. Such sample has to be measured in the solid state as it is. Although the transmission method can be applied to the CD measurement for such solid samples, it needs sample preparation such as making a pellet and also, if the sample dilution is required, it is not easy to recover the sample. For solving those difficulties in such transmission method, diffuse reflection (DR) CD method has been recommended. This application note illustrates the DRCD measurement using model DRCD-575 optimized for the J-1500 CD spectrometer with the multi-probe function.

DRCD is a method, in which the sample powder is located at the measurement point for diffuse reflection in integrating sphere and the CD is measured by utilizing diffuse reflection light and therefore, the DRCD can be effectively applied to the powder sample. However, in CD measurement of such solid sample, the influence of LD (linear dichroism) derived from the optical anisotropy of solid sample may have to be taken into consideration in order to minimize the CD artifact. The model J-1500 CD spectrometer allows the users to estimate the CD artifact easily by an incorporated quad digital lock-in amplifier allowing multi-probe function which enables the simultaneous measurement of CD and LD. As an example of the DRCD measurement, L- and D-alanine powder were used as sample.