Chromatographic methods for characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers

The objective of this study was to develop chromatographic methods for the determination of the modification degree and the characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers (PEG–PAMAMs). The PEG–PAMAMs were prepared by reacting PAMAM generation 4 with monomethoxy PEG–nitrophenyl carbonate (mPEG–NPC). The modification degrees of PEG–PAMAMs were determined by quantifying 4-nitrophenol released from mPEG–NPC after PEGylation reaction using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The PEG–PAMAMs, which have poor UV absorbances, were characterized by HPLC with charged aerosol detection. This study demonstrates that the combination of these two detectors is a powerful tool for the preparation and characterization of PEG–PAMAMs.