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.

For GPC Basics, please read the Waters Beginner's Guide to Size Exclusion Chromatography

Equipment
Pump: Waters Alliance HPLC System, e2695 Separation Module
Detectors:    Waters 2414 Differential Refractometer (RI) and Waters 2998 Photodiode Array Detector (PDA)
Solvent: DMF containing 0.01% of LiBr
Flow Rate: 0.35 mL/min
Injection: 20μL.

Columns for GPC-DMF:
2 Tosoh TSKgel Super columns + guard (1 HM-M  and 1 AWM-H)

Solvent: DMF with 0.01% 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.