Tandem mass spectrometry of polymeric materials
Mass spectrometry and tandem mass spectrometry (MS/MS) has been employed to analyse peptides (<600 daltons), synthetic polymers of low molecular weight (<10,000 daltons) and a mixture of polymer additives (300-1200 daltons). Mass spectrometry experiments were performed on a four sector mass spectrometer, a tandem quadrupole mass spectrometer and a time-of-flight instrument. High and low energy collision induced dissociation (CID) spectra were obtained by means of a four sector mass spectrometer and a tandem quadrupole instrument respectively. Surface induced dissociation (SID) spectra of peptides were obtained by means of a four sector mass spectrometer with a modified collision cell in the third field free region. Sequence data were generated by SID from protonated and cationated precursor ions of all four peptides analysed. Furthermore, broad metastable ion peaks were observed in the spectra, arising from fragmentation of precursor ions in the field free region between the electric sector and the magnetic sector of the second mass spectrometer. Field desorption was a good ionisation technique for the generation of molecular weight information from the polymer additives used. High energy eID was found to be more applicable than low energy eID to the structural determination of polymer additives as characteristic ions were observed in the spectra. Mechanisms have been proposed for the generation of some of the fragment ions observed. Ultraviolet-matrix assisted laser desorptionlionisation spectra of synthetic polymers of low molecular weight (<10,000 daltons) were used to calculate molecular weight averages. Furthermore, end group information was also obtained from CID spectra of the same polymer samples. End group and structural information was also obtained from polystyrene and a substituted polystyrene by means of FD-MS/MS.