Analysis of amlodipine in human plasma by liquid chromatography-mass spectrometry

A simple, sensitive, and specific liquid chromatographic method coupled with electrospray ionization (ESI)-mass spectrometry for the determination of amlodipine is developed. After extraction by ethyl acetate using nicardipine as the internal standard, solutes are separated on a C18 column with a mobile phase of methanol-1% HAc (65:35). Detection is performed on an air pressure ionization single quadruple mass spectrometer equipped with an ESI interface and operated in positive-ionization mode. Amlodipine quantitation is realized by computing the peak-area ratio (amlodipine-nicardipine) of the extracts analyzed in single ion monitoring mode (m/z 431 and m/z 480 for amlodipine and nicardipine, respectively) and comparing them with the calibration curve (r = 0.9991).