Determination of Etoricoxib in Human Plasma Using Automated On-line Solid-phase Extraction Coupled with Lc-apci/ms/ms

A liquid chromatography-tandem mass spectrometry method with atmospheric pressure chemical ionization (LC-APCI/MS/MS) was validated for the determination of etoricoxib in human plasma using antipyrin as internal standard, followed by on-line solidphase extraction. The method was performed on a Luna C 18 column and the mobile phase consisted of acetonitrile:water (95:5, v/ v)/ammonium acetate (pH 4.0; 10 mM), run at a flow rate of 0.6 mL/min. The method was linear in the range of 1-5000 ng/mL (r>0.99). The lower limit of quantitation was 1 ng/mL. The recoveries were within 93.72-96.18%. Moreover, method validation demonstrated acceptable results for the precision, accuracy and stability studies.