Development of a size exclusion chromatography method for the determination of molar mass for poloxamers

An aqueous size exclusion chromatography (SEC) method for determination of the molar mass of poloxamers 188 and 407 has been developed as an alternative to the pharmacopoeia methods. During the development work two different columns and several different eluent compositions were investigated. With a PL-aquagel-OH column, non-exclusion behaviour was obtained. A TSKgel column gave good separation of both poloxamers. The best separation was obtained with an eluent consisting of sodium chloride (0.01 M)-methanol (90:10, v/v) on the TSKgel column. The method was shown to be linear within the elution time of the two poloxamers and to have acceptable precision. The results from the SEC method was compared to results obtained using SEC with online multi angle light scattering detection (MALS) and to results obtained with matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS).