Gel permeation chromatography method for GPC system definition and performance evaluation

摘要

AbstractA practical method for the overall performance evaluation of a GPC system (columns) is described. System performance is defined as the ability of the system to give experimental M̄nand M̄wvalues (uncorrected for instrumental spreading and other distorting factors) which agree with the theoretical values, and it is expressed as the per cent deviation between the theoretical and experimental values. The method consists of running blends of monodispersed polystyrene standards of known compositions through the GPC system to be evaluated. From the resulting chromatograms, their M̄nand M̄wvalues are calculated (experimental). The theoretical M̄nand M̄wvalues of the same standards are also calculated from the formulasdocumentclass{article}pagestyle{empty}begin{document}$$ bar M_n = frac{{Sigma M_i N_i }}{{Sigma N_i }}{rm and }bar M_w = frac{{Sigma M_i ^2 N_i }}{{Sigma M_i N_i }} $$end{document}on the basis of their composition. By plotting the per cent difference of the experimental values from the theoretical values versus the theoretical values on a semilog scale, the overall performance of the GPC system under investigation is pictorially depicted. Results indicate that performance under experimental conditions can vary significantly from system to system. Results also indicate that performance of a system can be improved and optimized by proper column selection and system modifica