ELECTROSPRAY-IONIZATION FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRIC CHARACTERIZATION OF HIGH-MOLECULAR-MASS STARBURST(TM) DENDRIMERS

A series of Starburst (TM) polyamidoamine (PAMAM) dendrimers, built fr om a tetrafunctional ethylenediamine (EDA) core, generations 1 to 10 ( G1-G10), and covering a wide range of charge state distributions (i.e. from m/z similar to 500 to m/z similar to 15000), have been investiga ted by electrospray ionization (ESI) Fourier transform ion cyclotron r esonance (FT-ICR) mass spectrometry. High resolution mass spectra for lower generation dendrimers (G1, M-r similar to 1429 u to G5, M-r simi lar to 28825 u) allowed characterization of the polydispersity of thes e systems, providing a basis for improving synthetic strategies and ch aracterizing surface-modified dendrimers. The relationship between cha rge state in the gas phase and molecular mass of these spherical macro molecules is reported and used to estimate the stoichiometry of a G5 P AMAM dendrimer - polyclonal rabbit IgG immunoconjugate. The results pr esented herein represent the highest molecular mass species yet detect ed by FT-ICR MS with the exception of measurements based upon individu al ion detection. (C) 1997 Elsevier Science B.V.