Do column frits contribute to the on-column, flow-induced degradation of macromolecules?
Andre M. Striegel
Flow-induced, on-column degradation is a major hindrance to the accurate characterization of ultra- high molar mass macromolecules and colloids. This degradation is a direct result of the large shear rates which are generated within the column, which cause chain scission to occur both in the interstitial medium and, it has been postulated, at the packing particle pore boundary. An additional putative source of degradation has been the column frits, though little experimental evidence exists to either support or refute this claim. To this effect, the present experiments examine the role of the frits in the degradation of high molar mass macromolecules. Two narrow dispersity polystyrene standards, the molar mass of which differs by a factor of two, were analyzed on three different size-exclusion chromatography (SEC) columns, each with frits of different pore size, at various flow rates. In the smallest particle size column, which also contained the smallest frits and which was packed with the smallest diameter particles, the larger standard was forced to degrade by increasing the flow rate of the mobile phase. During the course of the latter portion of the study, the inlet and the outlet frits were removed from the column, in stepwise fashion. It was concluded that neither frit played any appreciable role in the degradation. Results of our studies were applied to explain previously observed degradation in ultra-high pressure liquid chromatography of polymers. The general conclusion arrived at herein is that the column frits are likely to have a negligible role, or no role at all, in polymer degradation for cases where the frit radius if larger than or equal to the hydraulic radius rc of the column.
Do column frits contribute to the on-column, flow-induced degradation of macromolecules?, Journal of Chromatography A, [online], https://doi.org/10.1016/j.chroma.2014.07.033
(Accessed July 31, 2021)