RAPID-DETERMINATION OF A NEW ANGIOTENSIN-CONVERTING ENZYME-INHIBITOR,IMIDAPRIL, AND ITS ACTIVE METABOLITE IN HUMAN PLASMA BY NEGATIVE-ION DESORPTION CHEMICAL IONIZATION TANDEM MASS-SPECTROMETRY (MS MS)/

A very rapid and highly sensitive method using desorption chemical ion ization (DCI)-tandem mass spectrometry (MS/MS) with selected reaction monitoring is reported for the simultaneous determination of imidapril and its active metabolite (M1) in human plasma. Imidapril and M1 in p lasma were extracted by a C18 solid phase extraction cartridge after d eproteinization, and derivatized with pentafluorobenzyl bromide. One m ul of prepared sample was applied to the DCI filament and analyzed by DCI/MS/MS within a few minutes. The limits of determination of imidapr il and M1 were 0.2 and 0.5 ng/ml in human plasma, respectively. The fe atures of this method make it appropriate for use in pharmacokinetic s tudies with human plasma after oral administration of imidapril.