Endgroup determination of synthetic polymers by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Electrospray ionization (ESI) was performed on a Fourier transform ion cycl otron resonance mass spectrometer for the endgroup and monomer mass determi nation of three poly(oxyalkylene)s in the mass range of 400-8000 Da. A comb ined use of the multiple charge states observed with ESI, leads to a threef old increase in accuracy of the endgroup and monomer determination. The imp rovement is attributed to the increased number of datapoints used for the r egression procedure, yielding more accurate results. Endgroup masses are de termined with a mass error better than 5 and 75 millimass units for the mol ecular weight range of 400-4200 and 6200-8000 Da, respectively. A mass erro r of better than 1 millimass unit was observed for all monomer mass determi nations. With ESI, endgroup and monomer masses have been determined for pol y(ethylene glycol) oligomers with a mass higher than 8000 Da. This is almos t two times higher than observed with matrix-assisted laser desorption/ ion ization on the same instrument. (J Am Soc Mass Spectrom 2000, 11, 536-543) (C) 2000 American Society for Mass Spectrometry.