Analysis MethodInvestigation of sample preparation for high temperature gel permeation chromatography using a low solvent consumption method

The study explored the optimum conditions for sample preparation of polyolefins for high temperature gel permeation chromatography (GPC) recommended by ASTM D 6474, and the potential for reducing solvent consumption by using columns with reduced internal diameter. A polypropylene sample with high crystallinity and high molecular weight was selected, because this is one of the most difficult polyolefins to analyze by GPC. Sequences of injections covering 20 h showed that, at 160 °C, 2 h is enough to dissolve this sample, and that the antioxidant concentration is the critical parameter in obtaining reproducible GPC results. By using one column with an internal diameter (ID) of 4.6 mm and a flow rate of 0.3 mL/min, instead of the classical set of 3 columns of 7.5 mm ID and a flow rate of 1 mL/min, the solvent consumption can be reduced to about 10%.