A sensitive and rapid HTLC-ESI-MS/MS method with an advanced online sample preparation was developed for determination of the γ-secretase inhibitor MK-0752 in human plasma using an internal standard. Plasma samples (100 μL) were diluted and injected directly onto an online extraction column (Cohesive Cyclone MAX 0.5×50 mm, > 30 μm), the sample matrix was washed out with an aqueous solution, and retained analytes were eluted out and transferred directly to the analytical column (Phenomenex Gemini 3μ C18 110A, 50×2.0 mm at 50°C) for separation using a gradient mobile phase. The eluted analytes were then detected on an API-3000 LC–MS/MS System with ESI and a negative multiple reaction monitoring mode. The monitored ion transitions were m/z 441→175 for MK-0752 and 496→175 for the internal standard. Online extraction recoveries were 81%. The method was validated and was linear in the range of 0.05–50 μg/mL. Within-day and between-day precisions were < 8.6%, and accuracies were 0.7% and 7.1%. This method was applied to the measurement of plasma MK-0752 levels in a Phase I study of pediatric patients with recurrent or refractory brain tumors.
Keywords: MK-0752, online sample preparation, high turbulence liquid chromatography (HTLC), electrospray tandem mass spectrometry (ESI-MS/MS)