Pyrolysis—gas chromatography/mass spectrometry and electron impact-, fast atom bombardment-mass spectrometry of sulfonylureas

Four sulfonylurea herbicides, i.e. chlorsulfuron, metsulfuron methyl, thiameturon methyl and chlorimuron ethyl, were analyzed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), electron impact mass spectrometry (EIMS) and fast atom bombardment mass spectrometry (FABMS). Pyrolysis at 800°C produced a range of fragments characteristic of the original molecules; the most important were the heterocyclic amine, the heterocyclic isocyanate, and the sulfonamide. Pyrograms with semiquantitative analysis of the main peaks are reported. EIMS produced similar fragments. Py-GC/MS affords the prospect of using GC as an alternative to HPLC for the study of the unvolatile and thermally unstable sulfonylureas without derivatization.