Laser light‐scattering characterization of gelatin in formamide

Abstract

AbstractLaser light scattering (LLS) including angular dependence of absolute integrated scattered intensity (static LLS) and of the spectral distribution (dynamic LLS) has been used successfully to characterize gelatin in formamide at room temperature. In static LLS, the use of formamide as a single solvent instead of an aqueous salt solution avoids the well‐known problem of preferential sorption of salts in the domain of gelatin molecules. Therefore the true weight‐average molecular weight Mw, the z‐average radius of gyration, and the second virial coefficient have been determined. In dynamic LLS, precise measurements of the intensity‐intensity time correlation function permit a Laplace inversion to obtain an estimate of the normalized characteristic linewidth distribution which could be reduced to a translational diffusion coefficient distribution, G(D). This report shows that the calibration between D and M can be established from Mw and G(D) by using only two broadly distributed gelatins instead of a set of narrowly distributed gelatin standards. After establishing a calibration between D and M, we were able to estimate the molecular weight distribution of gelatin from G(D). © 1994 John Wiley & Sons, Inc.