APPLICATION OF LIQUID-CHROMATOGRAPHY THERMOSPRAY MASS-SPECTROMETRY TO THE ANALYSIS OF POLYESTER OLIGOMERS

The products obtained by depolymerization of poly(ethylene terephthalate) (PET) with ethylene glycol were characterized by liquid chromatography-thermospray mass spectrometry (LC-TSP-MS). Discharge ionization produced intense negative ion mass spectra containing both acetate attachment and radical molecular anions of PET oligomers. Both full-scan and multiple ion detection modes were evaluated for the structural identification of the LC peaks. Improved performance of the LC-TSP-MS analysis could be obtained by derivatization of the depolymerization mixture with perfluoroanhydrides. This approach gave rise to a tenfold decrease in detection limits and allowed the identification of several additional components of the mixture. Major constituents of the glycolysis mixture were found to be linear and cyclic PET oligomers, diethylene glycol-containing oligomers and monoacetyl derivatives of linear oligomers.