Analytical Instrument Documents

MSTips No. 399

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOFMS) is a powerful tool for polymer analysis. Since MALDI mainly produces singly charged ions, the m/z values in the mass spectrum is the masses of the polymer ions. By using high mass-resolution MALDI-TOFMS, it is possible to easily distinguish polymer series based on differences in repeating units and end group composition, and to calculate the molecular weight distribution of each series. Recently, the Kendrick Mass Defect (KMD) method has made it possible to easily visualize polymer series contained in complex high mass-resolution mass spectra. When the molecular weight of a sample is several thousand or more, it is known that electrospray ionization (ESI), a typical soft ionization method along with MALDI, tends to produce mainly multiply charged ions, making it difficult to directly analyze the mass spectrum, let alone perform KMD analysis. Therefore, the combination of the high mass-accuracy of the JMS-S3000 “SpiralTOF™-plus2.0” and KMD analysis is particularly effective for the analysis of copolymers. Here, we will report on the binary copolymer search function newly added to msRepeatFinder V6 and the resulting compositional analysis of EO-PO copolymers using the degree of polymerization plot.