Sample preparation
The protein precipitation was the preferred choice of seperation because
of the minimized steps in extraction of drug from matrix. Aliquots of
100 µL plasma samples and 50 µL of IS (10 µg/mL) was added into 10 mL
centrifuge tube and vortexed for 5 s. The mixture was precipitated with
500 µL acetonitrile. After vortexing for 30 s, the samples were
centrifuged at 5500 rpm for 10 min. An aliquot of 5 µL of the
supernatant was injected into the LC–MS/MS system for analysis.