CHARACTERIZATION OF SYNTHETIC-POLYMERS BY SIZE-EXCLUSION CHROMATOGRAPHY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

Size-exclusion chromatography/electrospray ionization mass spectrometr y (SEC/ESI-MS) was studied for the characterization of polydisperse sy nthetic polymers having different polarities. Reconstructed-ion curren ts and the number of oligomers observed were found to depend strongly on both the level of cationization salt and the cone voltage setting, with the less polar polymers requiring a higher salt concentration in the tetrahydrofuran mobile phase. The polymers, poly(tetrahydrofuran), poly(methylmethacrylate), polyester and poly(styrene) were characteri zed in terms of repeating units and end-groups and used to compute acc urate calibration curves for the SEC column. Thus the on-line SEC/ESI- MS approach can overcome the drawbacks of both SEC (unreliable calibra tion) and MS (molecular weight distributions skewed to lower masses in cases of polydisperse polymers). In addition, the flexibility of SEC/ ESI-MS using a tri-coaxial sheath-dow interface for post-column additi on of cationization salt in appropriate solvents was briefly studied.