Development and Validation of a Liquid Chromatography Coupled with Atmospheric-Pressure Chemical Ionization Ion Trap Mass Spectrometric Method for the Simultaneous Determination of Triptolide, Tripdiolide, and Tripterine in Human Serum

A sensitive method has been developed and validated for the simultaneous determination of triptolide, tripdiolide, and tripterine in human serum using hydrocortisone as an internal standard (IS). After triptolide, tripdiolide, and tripterine in human serum were extracted with ethyl acetate, the extracts were separated on an XDB C18 column (30 mm × 2.1-mm i.d., 3 µm) using a mobile phase of acetic acid/ammonium acetate (5 mmol/L, pH 4.5)/acetonitrile/methanol in gradient elution. Detection was performed by high-performance liquid chromatography coupled with atmospheric-pressure chemical ionization ion trap mass spectrometry in negative multiple reaction monitoring mode. The transition ions m/z 359 → 340, m/z 375 → 357, m/z 449 → 405, and m/z 419 → 329 were selected for the quantification of triptolide, tripdiolide, tripterine, and IS, respectively. The linear range was 1.0–100.0 ng/mL, the absolute recoveries were between 78.3 and 89.2%, the relative recoveries were between 88.1 and 94.6%, and the limits of quantification in human serum were 0.5–1.0 ng/mL for the three target compounds. The intra- and interday relative standard deviations were less than 11.9% and 13.0%, respectively. This method was found to effectively and simultaneously determine trace triptolide, tripdiolide, and tripterine in human serum and can be suitable for clinical and toxicological studies.