Combined differential light scattering with various liquid chromatography separation techniques.

Measurements of scattered light intensity as a function of angle (often called differential [l] or total intensity light scattering) from an eluting sample separated into its particulate/molecular constituents by various chromatographic means permit the improvement of subsequent analyses {in the Rayleigh-Gans-Debye (RGD) approximation [2]} in three distinct ways. First, the ability to make repeated simultaneous measurements at several angles improves the precision of the derived weight averaged mass values. Secondly, for particles/molecules which are sufficiently large, the z-average square radius (‘radius of gyration’ squared) may be derived [3], as well. Finally, if a distribution of particles/molecules is present in the sample and they have been sufficiently separated so that both mass and radius may be derived at each elution fraction, then by plotting the root z-average square radius against the weight averaged mass on a log-log scale, the molecular/particulate configuration (rod, sphere, coil, etc.) may be deduced [4]. For particles that do not satisfy the RGD criteria, a series of other deductions from the recorded data are possible, including size, refractive index, and structural non-homogeneity. For macromolecules, and other particles of mean radius u satisfying the RGD approximation criteria: