EFFECTS OF COLUMN COMBINATIONS ON THE MEASUREMENT OF AVERAGE MOLECULAR-WEIGHTS AND THE MOLECULAR-WEIGHT DISTRIBUTION IN HIGH-PERFORMANCE SIZE-EXCLUSION CHROMATOGRAPHY

Average molecular weights and the integral molecular weight distribution curves for polystyrene NBS 706, NBS 705 and one broad polystyrene measured using different column combinations have been compared. The average molecular weights were not affected by the column combination, but the integral molecular weight distribution curves showed definite differences among several column sets. The most probable integral distribution curve will be obtained from a column packed with mixed gels of different porosity. A column combination without a gap in porosity or with many different gel porosities is preferable. The column set should have an exclusion limit of about ten times the weight-average molecular weight for the polymer sample. © 1979.