A simple ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method was developed and fully validated to simultaneously determine levothyroxine (LT4) and liothyronine (LT3) in human serum. Sample preparation was done through protein precipitation with acetonitrile. HyPURITY C18 column was selected to achieve rapid separation for LT4 and LT3 within 4 min. Electrospray ionization (ESI) under multiple reaction monitoring (MRM) was used to monitor the ion transitions for LT4 (m/z 777.54→731.52), LT3 (m/z 651.64→ 605.65) and internal standard LT4-D3 (m/z 780.53 →734.19), operating in the positive ion mode. The method was proved to be accurate (82.35% to 113.56%) and precise (0.73% to 8.28%) over concentration range of 50.37 ng/ml – 300.13 ng/ml for LT4 and 0.5 ng/ml – 50.37 ng/ml for LT3. The validated method could be applied for pharmacokinetic study or bioequivalence testing of combination products of LT4 and LT3.
Keywords: Levothyroxine; Liothyronine; Ultra Performance Liquid Chromatographic; Mass Spectrometry; Human Serum
Development and validation of an LC-MS/MS method for determination of phencyclidine in human serum and its application to human drug abuse cases
