1 Scope
This document specifies the determination of the molar-mass distribution and the average molar mass values M n (number average) and M w (weight average) of polymers that are soluble in water by gel permeation chromatography ( GPC ).
NOTE Also known as size exclusion chromatography (SEC).
This method is applicable to neutral polymers and polyanions (e.g. polycarboxylates, polysaccharides, fully hydrolyzed polyvinyl alcohols and high-molecular polyethylene oxides). It is not applicable to polycations [e.g. polyvinylpyrrolidone, polyvinylpyridine, salts of poly(diallyl‑N,N‑dimethyl‑azacyclopentane), chitosan].
Despite good solubility in the mobile phase and even though the chromatograms obtained show good repeatability, it is possible that this method cannot be used with certain polymer types because of specific interactions (e.g. adsorption) within the sample/eluent/column system (see also Clause 12).
The conditions specified in this document are not applicable to the GPC analysis of polymer samples with M w values greater than 10 6 g/mol and/or polymers with elution limits outside the calibration range (see 7.6 and Annex C).
This document includes no correction methods (e.g. for the elimination of peak broadening). If absolute molar mass values are required, an absolute method (e.g. membrane osmometry for M n or light scattering for M w ) can be used.