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Gel Permeation Chromatography (GPC) is a separation method for the determination of molecular weight averages (Mn) and molecular weight distribution (PDI=Mw/Mn). The testing report can include calibration plot, chromatogram, number average molecular weight and PDI of the polymer. GPC-DMF is using DMF as a solvent. Gel Permeation Chromatography (GPC) separates molecules on the basis of hydrodynamic size (not Mw). The large molecules move more rapidly through the GPC column, and in this way the mixture can be separated. The elution volume of a molecule is related to its hydrodynamic volume. To relate the elution volume to the molecular weight of a polymer, a calibration with molecular weight standards is needed.
Pump: Waters Alliance HPLC System, 2695 Separation Module
Detectors: Waters 2414 Differential Refractometer (RI) and Waters 2998 Photodiode Array Detector (PDA)
Solvent: DMF containing 0.1% of LiBr
Flow Rate: 1 mL/min
Columns for GPC-DMF:
Four Visco Gel I-Series Columns from Viscotek, dimensions= 7.8 mm x 30cm:
2 columns: IMBHMW-3078 (Mixed Bed High MW)
2 columns: IMBLMW-3078 (Mixed Bed Low MW)
solvent: DMF with 0.1% LiBr
The addition of the electrolytic salt, LiBr (0.01%), stabilizes the effects whether associated with the polymer or the columns, enabling
normal fractionation to occur.
calibration: vs polystyrene standards, per request vs PEO or PMMA.