Ethylene Oxide-Propylene Oxide block Copolymer Analysis by MALDI Spiral-TOF/TOF

Many polymeric materials such as synthetic resins consist of copolymers that can have a very complicated chemical structure. For the structural analysis of those polymeric materials by using mass spectrometry (MS), high-resolving power and high mass accuracy are necessary. Conventional MALDI-TOFMS systems based on reflectron ion optics do not have enough resolving-power for the analysis of such complex polymeric materials. Ethylene oxide-Propylene oxide block copolymers (M-n similar to 1,100) were analyzed by a newly developed MALDI Spiral-TOF/TOF system. It was possible to observe molecular weight distributions of every kind of ethylene oxide which have different degree of polymerization and to measure the exact mass values of two peaks separately around the m/z 1,000 area that have almost same m/z values (m/z difference was 0.027 Da). In addition, the MS/MS spectrum of a certain precursor ion was also observed. the MALDI Spiral-TOF/TOF system has the capability of monoisotopic ion selection of precursor and high energy collision induced dissociation for MS/MS measurement. It was shown that the fragment series could be easily estimated by acquired product ion spectra. Those results suggest that the MALDI Spiral-TOF/TOF system can be a powerful tool for block copolymer analysis.