Several procedures have been already developed to determine the average-molecular weight (M) for polymers. However, determination of M with an optimal procedure, given a good accuracy is a major issue for research groups. This mini-review described three following procedures for determination of M with a good accuracy: (a) viscometry using intrinsic viscosity ([η]) data and Mark–Houwink–Sakurada (MHS) equation; (b) size exclusion chromatography (SEC) with a single concentration detector; and (c) SEC equipped with two detectors, concentration and viscometry detectors. The following conclusions were made: (1) in viscometry, the accuracy of M depends on the accuracy for the MHS equation constants, K and a. The values K and a, depend on the nature of polymer, quality of the solvent, polydispersity of the polymer samples, molecular weight range, and temperature. of polymer solution; (2) in SEC with a single detector, the value of M was determined, based on the calibration curve (log M against retention time). The polymer standard should have the same conformation in solution with the polymer under investigation, otherwise an unsatisfactory value for the M will be obtained; and (3) SEC equipped with the two detectors, the value of M for the investigated polymer was determined with a good accuracy. The polymer could have any conformation in solution either similar or different from the polymer standard.

Molecular weight, Intrinsic viscosity, Size exclusion chromatography