Representative Polyisobutylene succinic anhydride (PIBSA) samples have been studied by different MS techniques including Electrospray Ionization Fourier Transform Ion Cyclotron Resonance MS (ESI-FTMS) (positive and negative modes), Atmospheric Pressure Chemical Ionization Fourier Transform Ion Cyclotron Resonance MS (negative mode), and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (positive and negative modes). Negative ion ESI-FTMS produces the best results. Differences between mono-succan and di-succan content can readily be observed. The source of the PIBSA (PIBSA-I and PIBSA-II processes) can be easily distinguished and the formation of methyl esters and amide derivatives can provide complementary data. The experiments have demonstrated the capabilities of mass spectrometry to detect and characterize such polymers samples. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012