Thermal decomposition of thonzonium bromide.

Thonzonium bromide, a quaternary ammonium compound used as a surface active agent in a phenylephrine nasal solution, gave a gas chromatographic peak which was proportional in height and area to its concentration. Quaternary ammonium salts are nonvolatile and polar, thus the peak was attributed to a thermal decomposition product. It was identified as hexadecyldimethylamine by spectroscopic analysis and comparison with an authentic sample. A second product was identified by mass spectroscopy as 2[(2-hexadecylmethylaminoethyl)(4-methoxybenzylamino)] pyrimidine, the desmethyl bromide product. These decomposition products were detected in stability samples of formulations.