Hybrid triple quadrupole‐linear ion trap mass spectrometry in fragmentation mechanism studies: application to structure elucidation of buspirone and one of its metabolites

Abstract

The use of a hybrid triple quadrupole-linear ion trap (QqQ(LIT)) mass spectrometer system for a comprehensive study of fragmentation mechanisms is described. The anxiolytic drug, buspirone, was chosen as a model compound for this study. With the advent of a QqQ(LIT) instrument, both the traditional quadrupole and the new linear ion trap scans (LIT) could be performed in a single LC run. In the past, a sample had to be run on two different instruments, namely, a triple quadrupole instrument (QqQ) and a 3D ion trap (3D IT) to obtain similar information. With the new QqQ(LIT) technology, collision-induced dissociation (CID) occur in a quadrupole collision cell, q2, and fragment ions are trapped and analyzed in Q3 operated in LIT mode. In this work, high-sensitivity product ion spectra of buspirone were obtained from the one-stage 'Enhanced Product Ion' scan (EPI) with rich product ions and no low mass cut-off. Furthermore, detailed fragmentation pathways were elucidated by further dissociation of each of the fragment ions in the EPI spectrum using MS(3) mode in the same run. The MS(3) scan was performed by incorporating CID in q2, and trapping, cooling, isolation, and resonance-excitation in Q3 when operating in LIT mode. This approach allowed unambiguous assignment of all fragment ions quickly with fewer experiments and easier interpretation than the previous approach. The overall sensitivity for obtaining complete fragment ion data was significantly improved for QqQ(LIT) as compared with that of QqQ and 3D IT mass spectrometers. This is beneficial for structure determination of unknown trace components. The method allowed structure determination of metabolites of buspirone in rat microsomes at 1 microM concentration, which was a 10-fold lower concentration than was needed for QqQ or 3D IT instruments. The QqQ(LIT) instrument provided a simple, rapid, sensitive and powerful approach for structure elucidation of trace components.

Discrimination Between Peptide O-Sulfo- and O-Phosphotyrosine Residues by Negative Ion Mode Electrospray Tandem Mass Spectrometry

“…However, similarly to the loss of 80 Da neutrals, the degree of the immonium ion formation varies considerably with phosphopeptide amino acid sequence [32]. Furthermore, multiple fragments observed in the low mass regions of the peptide positive ion mode CID spectra frequently interfere with pTyr immonium ion signal [31] and is usually not detectable in ion-trap CID spectra because of the low mass cut-off [33]. In the negative ion mode, we recently demonstrated that pTyr peptide monoanions undergo an extensive elimination of phosphoric acid (H 3 PO 4 ) [34], while the multiply charged peptide species produce phosphateinduced [M-nH-79] (n-1)-fragment ions [35].…”

In vitro metabolic stability and metabolite profiling of TJ0711 hydrochloride, a newly developed vasodilatory β-blocker, using a liquid chromatography–tandem mass spectrometry method

“…In contrast to luminescence, fluorescence, and radiometric analytical techniques, LC-MS/MS usually provides superior sensitivity and selectivity in supporting quantitative drug metabolism studies. More recently, hybrid triple quadrupole/linear ion trap (QqQ LIT ) mass spectrometer has been applied for metabolic property analysis with an addition of a high duty cycle in terms of the scanning capabilities using the linear ion trap [6,7]. This newly developed system has been used not only for quantitative analysis, but also for acquiring structural information data (product ion spectra) in the same analytical run.…”

Multistage Fragmentation of Ion Trap Mass Spectrometry System and Pseudo-MS3of Triple Quadrupole Mass Spectrometry Characterize Certain (E)-3-(Dimethylamino)-1-arylprop-2-en-1-ones: A Comparative Study

“…Additionally, ion trap cannot attain the parent ion and the lowest m / z daughter ion stable at the same time in the trap (low mass cut-off) in MS 2 scans. [12, 13]. To prove the capability of our pseudo-MS 3 hypothesis, a comparison with the real MS 3 in the ion trap is of great importance.…”