FRAGMENTATION OF BOSENTAN(R) (RO-47-0203) IN IONSPRAY MASS-SPECTROMETRY AFTER COLLISION-INDUCED DISSOCIATION AT LOW-ENERGY - A CASE OF RADICAL FRAGMENTATION OF AN EVEN-ELECTRON ION

For metabolic studies the fragmentation of a novel endothelin receptor antagonist, Bosentan, was investigated using ionspray tandem mass spe ctrometry. Bosentan belongs to the sulphonamide class and a complicate d and unexpected fragmentation at low energy, involving a radical frag mentation of an even-electron ion at the sulphonamide bond,is reported .