Reaction between Captopril and Ammonium Ion in the Gas Phase; Experimental and Theoretical Study

Captopril, 1-[(2S)-3-mercapto-2-methylpropionyl)-L-proline, is an orally activeinhibitor of angiotensin-converting enzyme (ACE) and widely use in the treatment ofhypertension. Many analytical methods have been used for captopril determination inbiofluids. Among the various methods of analysis, ion mobility spectrometry (IMS) providesfast, reliable, and sensitive response for many drugs including captopril [1]. Sample is ionized in reaction region of positive corona discharge IMS via the protontransfer reactions between the reactant ions and sample molecules. The peaks observed in theion mobility spectra can be assigned to ions formed by proton transfer, fragmentation andalso clustering with water molecules [2]. In this work, with consideration of theoreticalcalculation and experimental evidences, Suggestions on chemical ionization mechanism andionization products of captopril has been provided.