Automatic Data Capture and Analysis of Rayleigh Interference Fringe Displacements in Analytical Ultracentrifugation

Low speed sedimentation equilibriurn techniques using the analytical ultracentrifuge prouide a powerful tool for the analysis of molecular weight and molecular weight distributions of a wide range of macromolecular dispersions. The precision of the computed parameters depends citically upon the off-line rneasurernent and processing of photographic images of Rayleigh interference patterns, used to record the macromolecular solute distributions at equilibrium. We haue shown that it is possible to use a commercial scanning densitometer (LKB 2202), of a type widely found in laboratories in the life sciences, to capture a series of digitized scans across the fringe pattern; and haue deueloped a simple but highly fficient algorithm, based upon the iteratiue eualuation of a limited number of discrete Fourier coefficients, for data analysis. This algorithm is implemented in a Pascal program which can be run on the Ultroscan's own microcomputer. Results obtained show that a gain in precision of some S-fold has been obtained, as compared with preuiously fully automatic eualuation systems.