Abstract:

A sensitive, fast, and reproducible high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of diethylstilbestrol in human plasma was developed and validated. The plasma samples were pretreated by direct deproteinization with ethyl acetate. Daidzein was used as the internal standard. The separation was carried out on a Agilent Technologies 1200 series XDB C₁₈ column (2.1 mm×150 mm, 5 µm) with a mobile phase of acetonitrile-2.5 mmol/L ammonium acetate (60:40, v/v). Triple quadrupole mass spectrometric detection in negative ion mode was used for multiple-reaction-monitoring of the transitions atm/z 267.2→237.3 and m/z 253.2→132.3 for diethylstilbestrol and daidzein, respectively.The calibration curves were linear over the concentration range from 0.1 to 20 ng/mL (r² = 0.9984). The lower limit of quantificationwas 0.1 ng/mL (s/n mLs)for diethylstilbestrol, which was sensitive enough to perform pharmacokinetic studies after diethylstilbestroladministration. Inter-day and intra-day precisions were no more than 7% with accuracies of 90%-105%. This method could be applied to therapeutic drug monitoring of diethylstilbestrol, which is helpful for evaluating the clinical efficacy and safety of diethylstilbestrol.

Key words: HPLC-ESI-MS/MS, Diethylstilbestrol, Human plasma