Biomer is a segmented polyether/polyurethane in which the monomer of the polyether is tetramethylene oxide and the urethane linkages are with toluene-2,4-diisocyanate. Both the positive- and negative-ion laser desorption mass spectra of Biomer show peaks corresponding to fragments from the polyether and the polyurethane. Avcothane is also a segmented polyether/polyurethane, however polydimethylsiloxane is blended into this polymer. The polyether of Avcothane is polypropylene glycol and the urethane bond is formed using toluene-2,4-diisocyanate. The positive and negative ion mass spectra of Avcothane contain peaks which have been assigned to polyether, polyurethane, and polydimethylsiloxane components.