ABSTRACT
The stock solutions of Nifekalant and Ornidazole at the concentration of 1 mg/mL were all dissolved under methanol and kept at 4ºC, respectively. A liquor of 0.5 mL plasma of sample plus 40 μL of IS (Ornidazole 10 μg/mL) was acidified by adding 50 μL of 0.1 mol/mL hydrochloric acid and 4 mL of ethyl acetate. Then it was vortex-mixed 2 min, centrifuged at 5000 r/min for 5 min. The water phase was discarded and 4 mL of organic phase was moved to a clean glass tube and dried under nitrogen in a 40 ºC water bath. The residue was reconstituted with 0.1 mL of mobile phase, centrifuged for 3 min, and 20 μL of it was injected for analysis.
