Analysis of Macromolecules Using Low- and Right-Angle Laser Light Scattering and Photon Correlation Spectroscopy

The objective of this paper is to introduce a new concept for a light scattering detector design which will combine the measurement of the diffusion constant of macromolecules and particles in a flowing stream with the measurement of the light scattering intensity at two angles. This new detector design will therefore provide the hydrodynamic radius of macromolecules eluting from any separation device and provide size information of a particle or molecular weight distribution from a chromatographic separation without any prior knowledge of sample concentration or chemical composition. This measurement operates using the principle of Dynamic Light Scattering (DLS) ( 1,2 ) also known as Quasi Elastic Light Scattering (QELS) and Photon Correlation Spectroscopy (PCS). The instrument is designed in such a way that several other measurements can also be made simultaneously in the same light scattering cell. These measurements include a 90° static (Raleigh) light scattering measurement as well as a 15° static (Raleigh) light scattering measurement. There is also a provision to make a 90° static depolarized light measurement in the future. The design concept of this device is detailed by Norman Ford in 1994 ( 3 ). This light scattering detector optics bench is commercially known as the PD2000.