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.