Separation of 57 species from solutions of commercial melamines and analysis by high resolution mass
spectrometry using electrospray ionisation and atmospheric pressure chemical ionisation is reported.
Structures for melamine-based crosslinked polymers were also confirmed with two orthogonal techniques
for characterisation of polymers: Fourier Transform Infrared Spectrometry (FTIR) and Nuclear
Magnetic Resonance spectroscopy (NMR), respectively.
Accurate mass measurements of melamine–formaldehyde resin structures were achieved in the ppm
range, using an internal calibration standard reserpine. Results were within 5 ppm of calculated formulae.
Relative isotopic abundances of [M+H]+ ions were evaluated for different fractions. Results were
independent of the mobile phase used. NMR studies also confirmed structures of fractions and their
thermal stability up to 70 ◦C. Differences in NMR spectra were explained by change of conformation and
it was confirmed that this is a reversible process by reheating samples. Stability at 70 ◦C was confirmed
by MS, since when the temperature of the ion transfer capillary in MS was set above this temperature
decomposition occurred.