Gel Permeation Chromatography (GPC) is a separation method for the determination of molecular weight averages (M_n) and molecular weight distribution (PDI=M_w/M_n). 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 M_w). 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.

Equipment
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
Injection: 100μL.

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.