A Novel Derivatization Reagent in the Determination of the Number of OH End Groups in Poly(ethylene glycol) by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

The potential of a novel derivatization reagent, trifluoroacetic anhydride (TFAA), in determining the number of OH groups in poly(ethylene glycol) (PEG) was investigated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The MALDI mass spectra of the products revealed peaks of sodiated derivative cations, whose shift by the respective increments, Δm/z: 96 × number of OH, allowed for the determination of the number of end functional groups with active hydrogens. In the present study, complete acylation of OH groups by TFAA proceeded rapidly, and only required mixing in acetonitrile solvent without purification. As a result, the number of OH end groups of PEG could be determined rapidly.