Identification of autoxidation and photodegradation products of ethynylestradiol by on-line HPLC–NMR and HPLC–MS

Abstract HPLC–NMR, HPLC–MS, and HPLC–UV were used to characterize the predominant solution autoxidation and photodegradation products of ethynylestradiol ( 1 ). A hydroperoxide ( 2 ) and a series of isomeric dimeric oxidation products ( 3 – 7 ), were identified.