A rapid and sensitive liquid chromatography–tandem mass spectrometric assay for moexipril,an angiotensin‐converting enzyme inhibitor in human plasma

A simple, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of angiotensin‐converting enzyme inhibitor, moexipril, in human plasma. Benazepril was used as an internal standard (IS). Analyte and IS were extracted from the human plasma by liquid–liquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on a C₁₈ column by using a mixture of methanol and 0.1% formic acid buffer (85:15, v/v) as the mobile phase at a flow rate of 0.5 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.2–204 ng/mL. The multiple reaction‐monitoring mode was used for quantification of ion transitions at m/z 499.4/234.2 and 425.2/351.1 for moexipril and IS, respectively. The results of the intra‐ and inter‐day precision and accuracy studies were well within the acceptable limits. A run time of 2.0 min for each sample made it possible to analyze more than 400 plasma samples per day. The proposed method was found to be applicable to clinical studies. Copyright © 2012 John Wiley & Sons, Ltd.