A radio frequency glow discharge mass spectrometry (rf-GDMS) source is evaluated for future applications in the "fingerprint" characterization of polyphosphazene membranes. The rf-GDMS spectra of a series of bis(phenoxy)phosphazene polymers contain ions that originate from both the phosphazene backbone and the phenoxy moiety, resulting in signature ions of the polymer family. "Fingerprint" ions from the substituted R-group on the phenoxy moiety of the different derivatives allows the individual polymers to be distinguished from one another. The ability of the rf-GDMS source to characterize these materials directly in the solid state will be useful for the continued application of these polymers as separation membranes. (C) 2000 John Wiley & Sons, Inc.