Absorption and Interference Sedimentation Analysis of Bi-Component Polystyrene Solutions in Analytical Ultracentrifugation

Abstract

Sedimentation velocity runs were carried out using both absorption and interference detectors in an analytical ultracentrifuge for a bi-component polymer mixture and using two different data analysis programs. The concentrations of polymer were chosen between 0.11 g/L and 3.43 g/L and were kept constant for both absorption and interference detection systems so as to generate comparisons between the two apart from comparisons between the data analysis programs. The comparisons were achieved through the differential and cumulative distributions of sedimentation coefficient. Though the peak sedimentation coefficient values in both analysis programs were same, the distributions differed in peak broadness and axis interception. The amount of detected components in the mixture also differed in the analysis programs, with VelXLAI exhibiting better performance than Sedfit analysis. Similar observations were made for absorption and interference optics, except for the inability of the absorption optics to measure correctly above polymer concentration of 1 g/L.