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DETERMINATION OF LEVONORGESTREL IN HUMAN SERUM BY LIQUID CHROMATOGRAPHIC-ELECTROSPRAY TANDEM MASS SPECTROMETRY

A rapid, sensitive, and specific high-performance liquid chromatography electrospray tandem mass spectrometric method has been developed for the determination of levonorgestrel in human serum using norethindrone as an internal standard. Levonorgestrel was detected using multiple reaction monitoring mode after extracted from human serum by an ether extraction procedure. The calibration curve was linear over the range of 5–500 ng/mL (r 2 ≥ 0.999) with the limitation of detection of 1 ng/mL. The intra-day precision and accuracy, expressed as CV and RE, ranged from 0.5% to 10.1% and −0.2% to 2.2%. The inter-day precision and accuracy ranged from 2.1% to 13.6% and −2.3% to 3.3%. The mean recovery was 89.5% for levonorgestrel, and 90.2% for the internal standard.