Simultaneous UPLC-MS/MS assay for the detection of the traditional antipsychotics haloperidol, fluphenazine, perphenazine, and thiothixene in serum and plasma

Background: Most antipsychotic drugs that are commonly prescribed in the USA are monitored by liquid and gas chromatographic methods. Method performance has been improved using ultra high pressure liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). A rapid and simple procedure for monitoring haloperidol, thiothixene, fluphenazine, and perphenazine is described here. Method: Antipsychotic drug concentrations in serum and plasma were determined by LCMS/MS (Waters Acquity UPLCTQD). The instrument is operated with an ESI interface, in multiple reaction monitoring (MRM), and positive ion mode. The resolution of both quadrupoles was maintained at unit mass with a peak width at half height of 0.7 amu. Data analysis was performed using the Waters Quanlynx software. Serum or plasma samples were thawed at room temperature and a 100 mu L aliquot was placed in a tube. Then 300 mu L of precipitating reagent (acetonitrile-methanol [50:50, volume: volume]) containing the internal standard (0.12 ng/mu L Imipramine-D3) was added to each tube. The samples were vortexed and centrifuged. The supernatant was transferred to an autosampler vial and 8 mu L was injected into the UPLC-MS/MS. Utilizing a Waters Acquity UPLC HSS T3 1.8 mu m, 2.1 x 50 mm column at 25 degrees C, the analytes were separated using a timed, linear gradient of acetonitrile and water, each having 0.1% formic acid added. The column is eluted into the LC-MS/MS to detect imipramine D3 at transition 284.25 > 89.10, haloperidol at 376.18 > 165.06, thiothixene at 444.27 > 13924, fluphenazine at 438.27 > 171.11, and perphenazine at 404.19 > 143.07. Secondary transitions for each analyte are also monitored for imipramine D3 at 284.25 > 193.10, haloperidol at 376.18 > 122.97, thiothixene at 44427 > 97.93, fluphenazine at 43827 > 143.08, and perphenazine at 404.19 > 171.11. The run-time is 1.8 min per injection with baseline resolved chromatographic separation. Results: The analytical measurement range was 02 to 12.0 ng/mL for fluphenazine and perphenazine, and was 1 to 60.0 ng/mL for haloperidol and thiothixene. Intra-assay and inter-assay imprecisions (CV) were less than 15% at two concentrations for each analyte. Conclusions: By utilizing a LC-MS/MS method we combined two previously established analytical assays into one, yielding a 75% time-savings on set-up, and a significantly shortened analytical run-time. These changes reduced the turn-around time for analysis and eliminated interference issues resulting in fewer injections and increased column lifetime. (C) 2013 Elsevier B.V. All rights reserved.