Non-size exclusion behavior

Four primary problems must be considered in performing GPC studies of asphaltenes and maltenes. These are poor weight recoveries from GPC columns through sample adsorption, nonuniform detector responses for different sample sizes and/or types, uncertainty in selection of appropriate column calibrations, and non-size-exclusion behavior because of abnormal aromatics retention on Styragel. All these problems will be addressed in the following sections. 

Silanized silica gel has also been studied for the SEC analysis of cellulose trinitrate (37,38), using THF as the eluant. It was concluded that the elution behavior of the cellulose trinitrate sample was influenced by polyelectrolytic effects and was not based strictly upon size exclusion. The addition of 0.01 mol acetic acid per liter THF suppressed the non-size exclusion effects. Under these conditions, a universal calibration curve relating cellulose trinitrate and polystyrene could be established. 

The last factor is particularly important for the successful utilization of aqueous SEC in the investigation of the micellization process. In order to provide a realistic picture for the micellization equilibrium, the chromatographic system needs to meet several strict requirements The packing material and the eluent should be appropriately chosen to prevent the occurrence of non-size-exclusion phenomena and adsorption of micelles in the stationary phase. In all cases, mass balance of the material injected and recovered from the columns must be performed in order to verify the absence copolymer entrapment. Cross-linked copolymers containing either poly(vinyl alcohol) or polyCglycidyl methacrylate) as the hydrophilic component are the most widely used column packing materials for aqueous SEC. Both Shodex Protein KW (Showa Denko, Japan) and Micropak TSK-gel PW (Toyo Soda, Japan) columns have been reported to afford good information on the micellization behavior of PEO copolymers without... 

Duhin, P.L. Edwards, S.L. Mehta, M.S. Tomalia, D. Quantitation of non-ideal behavior in protein size-exclusion chromatography. J. Chromatogr. 1993, 635, 51. 

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