Analysis of mPEG5K-Phosphate using JMS-S3000 "SpiralTOF™-plus 2.0"
MSTips No. 402
The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is a powerful tool for polymer analysis. Since MALDI generates mainly singly-charged ions, m/z values from the mass spectrum are the same as the polymer ion's mass. In general, polymer analysis by MALDI-TOFMS is performed in positive ion mode because the sample solution is added to the matrix and cationizing agent solution. On the other hand, a polymer including sulfate or phosphate groups at the end group can be measured in the negative ion mode. In MSTips No. 333, we reported the measurement results of anionic surfactants less than m/z 1000. In this application note, we report the measurement of polyethylene glycol (average molecular weight 5000) having phosphate groups as an end group.