Quantification of estradiol cypionate in plasma by liquid chromatography coupled with tandem mass spectrometry: Application in a pharmacokinetic study in healthy female volunteers.

The combination of medroxyprogesterone acetate 25 mg + estradiol cypionate 5 mg is a highly effective, monthly injectable contraceptive. For the first time, this study presents the development and validation of a sensitive method for estradiol cypionate analysis in human plasma by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Aliquots (500 μL) of plasma were extracted with ethyl ether (100%) and derivatized with dansyl chloride.