Why after derivatized are the beta-blocker peaks eluting at the same retention time on GC? Does anyone have an explanation?

solutes: atenolol, propranolol and metoprolol derivatizing reagent: hexamethyldisilazane (HMDS) stationary phase; poly(5%phenyl+95%dimethylsiloxane) Detector: FID

15 August 2013 7,314 3 View