Separation and characterization of benzaldehyde-functional polyethylene glycols by liquid chromatography under critical conditions

Abstract

The distributions of non-, mono- and bi-functional benzaldehyde-substituted polyethylene glycols (PEGs) need to be accurately determined for biomedical applications. The baseline separation of PEGs and their derivatives based on the number of functional end groups without an obvious effect of molar mass is achieved by high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) using reversed-phase packing columns under critical isocratic elution conditions. The effects of organic solvent percentage, column temperature and buffer concentration on the retention times of PEGs and benzaldehyde-substituted PEGs have been investigated. The separation was mainly due to the hydrophobic interaction between the benzaldehyde end-groups and column packing. HPLC analysis can provide useful information to optimize the synthesis of functional PEGs. To our knowledge, this is the first report on separation of benzaldehyde-functional PEGs based on the functionality independent of the molar mass by isocratic elution.