Study of the electrospray ionization mass spectrometry of the proton pump inhibiting drug Omeprazole

Abstract

A detailed analysis of the product ion spectrum generated from the protonated molecule under ESI-MS/MS conditions using a triple quadrupole mass spectrometer is reported for the gastrointestinal proton pump inhibitor Omeprazole. Unambiguous molecular composition data of the fragment ions were obtained with the aid of regioselectively 14C-, 34S- and 18O-labeled analogs. Attempts have been made to provide rational pathways for the formation of the fragment ions from four protonated omeprazole species. These results will facilitate the characterization of the complex metabolic fate of Omeprazole in humans, which involves the excretion of at least 50 metabolites.

Simple quantification of lansoprazole and rabeprazole concentrations in human serum by liquid chromatography/tandem mass spectrometry

“…The collision-induced dissociation (CID) of protonated lansoprazole (m/z 370) and rabeprazole (m/z 360) resulted in a loss of the benzimidazole ring, leading to the main fragment ions at m/z 252 and 242. A proposed fragmentation for a compound of similar structure (omeprazole) has already been described [21]. As shown in Fig.…”

Rearrangement process occurring in the fragmentation of adefovir derivatives

“…In the MS 2 spectrum of 2, the most abundant fragment ion d was formed by the loss of 30 Da, which could be produced by three possible pathways: formaldehyde loss as for 1, elimination of two methyl radicals from the pivaloyloxymethyl chain 12 or formaldehyde loss from the pivaloyloxymethyl group. To elucidate the fragment pathways, two adefovir derivatives, 5 and 6, were synthesized in our laboratory.…”

Molecular formula analysis of fragment ions by isotope‐selective collision‐induced dissociation tandem mass spectrometry of pharmacologically active compounds

“…plot b). To confirm the putative molecular formula of all product ions, accurate mass measurements should be performed or regioselectively 14 C‐, 18 O‐, 34 S‐labeled analogs should be used, as reported by Weidolf et al , who proposed a fragmentation pathways by performing MS/MS and MS 3 experiments on the protonated isotope‐labeled omeprazole (Ome) ([ 14 C]Ome, ([ 18 O]Ome, [ 34 S]Ome). The proposed fragmentation scheme of omeprazole, using CID‐MS/MS, and suggested structure of the product ions is reported in Scheme .…”