Diffuse reflectance CD using an integration sphere

The preparation of pure enantiomers for pharmaceutical industry is part of mandatory safety requirements. Circular Dichroism is one technique to determine enantiomeric purity and it can be applied directly on solid samples.

Circular Dichroism measurements on solid samples have been done for years on pellets when sample proved to be insoluble or was showing structural change when changing media. The preparation of pellets is not straightforward and is also time consuming. To use an integration sphere for measuring Diffuse Reflectance (DR-CD) is an alternative to pellets that can be implemented in few minutes on MOS-500.

This application note illustrates the use of DR-CD accessory to determine enantiomeric purity of some alanine preparation (powder mixture of L and D forms). It also shows the negligible contribution of polarization artifact and the reliability of sample preparation.

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