MASS-SPECTROMETRIC ANALYSIS OF ADDITIVES IN POLYMER EXTRACTS BY DESORPTION CHEMICAL-IONIZATION AND COLLISIONAL INDUCED DISSOCIATION WITH B/E LINKED SCANNING

Desorption chemical ionization in combination with collisional induced dissociation and B/E linked scan proved to be a viable method for identifying additives in polyethylene extracts by mass spectrometry. In comparison with fast atom bombardment (FAB), much less fragmentation was observed with desorption chemical ionization (DCI) using ammonia as reagent gas. Furthermore, most likely due to the ''matrix effect'', not all the additives in the extracts were detected by FAB. The softness and the lack of matrix effect make ammonia DCI a better ionization technique than FAB for the analysis of additives directly from the extracts. Most likely due to higher collision energy, product ion mass spectra acquired with a double focusing mass spectrometer provided more structural information than the spectra obtained with a triple quadrupole mass spectrometer. Besides contamination from the seals of the supercritical fluid extractor, high and low density polyethylenes extracted with supercritical carbon dioxide produced similar results as with toluene.