Wavelength-Dependent Ultraviolet Photodissociation of Protonated Tryptamine

Abstract

Ultraviolet photodissociation (UVPD) experiments of protonated tryptamine ([Tryp+H]+) have been implemented by a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer combined with a wavelength-tunable optical parametric oscillator (OPO) laser. UVPD mass spectra under different laser wavelengths have been obtained, in which the dependence of the yield of fragment ions on the laser wavelength was observed. The UVPD spectrum of [Tryp+H]+ has been obtained in the range of 210–310 nm. Besides the previously reported two competitive channels of H loss and NH3 loss, two important channels of losing CH2NH and CH2NH2 units were observed and further studied by UV–UV tandem mass spectrometry and theoretical calculations. Interestingly, results show that the pair of competitive channels of CH2NH loss and CH2NH2 loss are both from the McLafferty-type rearrangement caused by ππ* electronic excited states. After the excitation, the two different dissociation pathways produce two different ion–neutral complexes, respectively. The wavelength-dependent dissociation and the existing competitive channels shown in this study reflect the diversity of UVPD processes of such organic molecules.

Versatile Double-Beam Confocal Laser System Combined with a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer for Photodissociation Mass Spectrometry and Spectroscopy

“…To make the alignment reliable, we performed experiments on some ions that we have previously studied with our separate IRMPD and UVPD experimental setups. The new results are consistent with those in the literature. ,− The effect of possible photo-electron capture dissociation (ECD), which has been reported by Shaw et al, has been checked and can be neglected in the subsequent experiments …”

“…The proposed experimental setup can be directly applied to IRMPD and UVPD action spectroscopic studies for ESI ions, as shown by the reported results of separate experiments. ,− The unique advantage of the new setup is that it can be readily applied to the secondary fragment ions generated from the UVPD or IRMPD processes, thus expanding the scope of the research. For instance, the UVPD mass spectra and action spectrum of the fragment ions generated by IRMPD may provide valuable information about their structures and electronic excited states.…”

“…The dissociation of gaseous ions in tandem mass spectrometry requires the deposition of sufficient internal energy into the target ions, which can be achieved by collisions with neutral molecules or suitable surfaces, capture or transformation of electrons, reaction with radicals, or photon excitation. − In the last case, both infrared (IR) and ultraviolet (UV) lasers have been applied. − For infrared multiphoton dissociation (IRMPD), the internal energy of the target ion increases in multiple steps until it reaches the threshold energy for dissociation. When tunable IR lasers are applied in such experiments, the IRMPD action spectra of the target ions are typically obtained by monitoring the dissociation of the precursor ions as a function of the applied wavelength. − Ultraviolet photodissociation (UVPD) has garnered significant interest in recent years. − Single-wavelength UV lasers, such as 266, 213, and 193 nm lasers, have been widely applied in mass spectrometric studies for the analysis of organic and biological molecules. − Extreme UV radiation has even been applied as an efficient method for ion activation and dissociation . UVPD action spectra can also be obtained by monitoring the laser-induced attenuation of precursor ions held inside a trapping region, such as the cell of a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. − …”

“…When tunable IR lasers are applied in such experiments, the IRMPD action spectra of the target ions are typically obtained by monitoring the dissociation of the precursor ions as a function of the applied wavelength. − Ultraviolet photodissociation (UVPD) has garnered significant interest in recent years. − Single-wavelength UV lasers, such as 266, 213, and 193 nm lasers, have been widely applied in mass spectrometric studies for the analysis of organic and biological molecules. − Extreme UV radiation has even been applied as an efficient method for ion activation and dissociation . UVPD action spectra can also be obtained by monitoring the laser-induced attenuation of precursor ions held inside a trapping region, such as the cell of a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. − Combined with mass spectrometry, IRMPD and UVPD spectroscopies have proven to be powerful techniques for structural elucidation over the past few years. These methods fully exploit the advantages of spectroscopy and mass spectrometry and benefit from the progress of advanced laser technologies, ion sources, and powerful ion traps.…”

Simultaneous quantitative chiral analysis of four isomers by ultraviolet photodissociation mass spectrometry and artificial neural network

“…The experimental setup has been described in our previous paper ( Shi et al, 2019 ; Zhang et al, 2020 ). Briefly, a 7.0 T Fourier transform ion cyclotron resonance (FT ICR) mass spectrometer (IonSpec, Varian, Inc., Lake Forest, CA) was applied here, combined with one commercial UV-Vis tunable laser (NT-342C, EKSPLA, Lithuania).…”