Sedimentation studies of single and bi-component polystyrene solutions in analytical ultracentrifugation by comparison of two analysis methods: effect of polymer concentration

Sedimentation analysis with interference detection optics was carried out for pure polymer as well as 1:1 polymer mixture samples as a function of polymer concentration in analytical ultracentrifuge. The data analysis was carried out using analysis programs of Sedfit and VelXLAI to elucidate the advantages and limitations of the analysis methods. The concentration dependency of the sedimentation coefficient was observed and the distributions became narrower on increasing the polymer concentration in both the methods. The peak sedimentation coefficients at different concentrations for both pure polymer as well as polymer mixture samples were same in both the methods though the sedimentation coefficients of the components in the mixture were slightly different from the sedimentation coefficient of the same component, when measured alone. The programs were observed to generate similar information in the case of pure polymer sample; however, in more complex polymer mixture sample, the Sedfit program was observed to have significant difference in the shape of the sedimentation coefficient distributions as well as in the amount of the components detected.