The complete structural elucidation of complex lipids, including glycerophospholipids, using only mass spectrometry represents a major challenge to contemporary analytical technologies. Here, we demonstrate that product ions arising from the collision-induced dissociation (CID) [M + Na](+) adduct phospholipids can be isolated and subjected subsequent gas-phase ozonolysis - known as ozone-induced (OzID) in linear ion-trap spectrometer. resulting CID/OzID experiment yields abundant are...

Glycerophospholipids (GPs) that differ in the relative position of two fatty acyl chains on glycerol backbone (i.e., sn-positional isomers) can have distinct physicochemical properties. The unambiguous assignment chain to an individual GP represents a significant analytical challenge. Here we describe workflow where phosphatidylcholines (PCs) are subjected ESI for characterization by combination differential mobility spectrometry and MS (DMS-MS). When infused as mixture, ions formed from...

Current atmospheric models underestimate the production of organic acids in troposphere. We report a detailed kinetic model photochemistry acetaldehyde (ethanal) under tropospheric conditions. The rate constants are benchmarked to collision-free experiments, where extensive photo-isomerization is observed upon irradiation with actinic ultraviolet radiation (310 330 nanometers). quantitatively reproduces experiments and shows unequivocally that keto-enol photo-tautomerization, forming vinyl...

Ozone-induced dissociation (OzID) is an alternative ion activation method that relies on the gas phase ion-molecule reaction between a mass-selected target and ozone in trap mass spectrometer. Herein, we evaluated performance of OzID for both structural elucidation selective detection conjugated carbon-carbon double bond motifs within lipids. The relative reactivity trends [M + X]+ ions (where X = Li, Na, K) formed via electrospray ionization (ESI) versus nonconjugated fatty acid methyl...

We attribute the two product-state distributions previously seen in CH₃CHO photodissociation to CH₃-roaming and H-roaming, unifying all previous experimental results.

The 1-deoxysphingolipids (1-deoxySLs) are formed by an alternate substrate usage of the enzyme, serine-palmitoyltransferase, and devoid C1-OH-group present in canonical sphingolipids. Pathologically elevated 1-deoxySL levels associated with rare inherited neuropathy, HSAN1, diabetes type 2 might contribute to β cell failure diabetic sensory neuropathy. In analogy sphingolipids, it was assumed that 1-deoxySLs also bear a (4E) double bond, which is normally introduced sphingolipid...

Here we report the development and optimization of a mass spectrometry imaging (MSI) platform that combines an atmospheric-pressure matrix-assisted laser desorption/ionization with plasma postionization (AP-MALDI-PPI) trapped ion mobility (TIMS). We discuss optimal parameters for operating source, characterize behavior variety lipid classes in positive- negative-ion modes, explore capabilities using murine brain tissue. The instrument generates high signal-to-noise numerous species, spectra...

Reactions with mobile protons occur under electrospray ionization (ESI) in many applications of mass spectrometry. Understanding how protonation isomers (protomers) form and molecular structure influences protomer interconversion provides fundamental insight into ESI mechanisms, which can then be exploited to rationalize ion mobility activation processes for robust analyte detection. Using ten arylamine systems, this paper establishes the key substrate properties that influence isomerism....

The ortho-benzyne diradical, o-C(6)H(4) has been produced with a supersonic nozzle and its subsequent thermal decomposition studied. As the temperature of is increased, benzyne molecule fragments: o-C(6)H(4)+Delta--> products. dissociation products were identified by three experimental methods: (i) time-of-flight photoionization mass spectrometry, (ii) matrix-isolation Fourier transform infrared absorption spectroscopy, (iii) chemical ionization spectrometry. At threshold temperature,...

The dynamics of the photodissociation CH(3)CHO into CH(3) + HCO products have been investigated at energies between 30,953 and 31,771 cm(-1), spanning threshold for radical production on triplet (T(1)) surface. A barrierless pathway to formed ground state (S(0)) surface was discovered established be an important reaction channel in acetaldehyde throughout this wavelength range. laser induced fluorescence (LIF) spectra recorded from dissociated above below T(1) barrier energy are quite...

Separation and structural identification of lipids remain a major challenge for contemporary lipidomics. Regioisomeric differing only in position(s) unsaturation are often not differentiated by conventional liquid chromatography-mass spectrometry approaches leading to the incomplete, or sometimes incorrect, assignation molecular structure. Here we describe an investigation gas phase separations differential-mobility (DMS) series synthetic analogues recently described 1-deoxysphingosine. The...

The detection and assignment of protonation isomers, termed protomers, gas-phase ions remains a challenge in mass spectrometry. With the emergence ion-mobility techniques combined with tuneable-laser photodissociation spectroscopy, new experimental combinations are possible to now meet this challenge. In paper, differences fragmentation electronic spectroscopy singly protonated (S)-nicotine (nicH+) analysed using action ultraviolet region field asymmetric ion mobility spectrometry (FAIMS)....

(O-acyl)-hydroxy fatty acids (OAHFAs) are a recently discovered class of endogenous lipids, generating significant interest for their correlation with enhanced glucose tolerance. Structural variants that differ in the position ester linkage have been described, including ω-OAHFA sub-class, plays key role stabilizing human tear film. Developing analytical tools rapid and unambiguous structural elucidation OAHFAs is essential to understanding diverse physiological functions.Commercially...

Despite the impacts - both positive and negative of atmospheric ozone for life on Earth, there remain significant gaps in our knowledge products, mechanisms rates some its most fundamental gas phase reactions. This incomplete understanding is largely due to experimental challenges involved study gas-phase reactions and, particular, identification short-lived reaction intermediates. Here we report direct observation stepwise halide anions iodide (I-) bromide (Br-) with produce XO3- (where X =...

The clearest dynamical signature of a roaming reaction is very cold distribution energy into the rotational and translational degrees freedom donor fragment (e.g. CO) an exceptionally hot vibrational in acceptor H2, CH4). These signatures were initially identified joint experimental/theoretical investigations H2CO CH3CHO are now used to infer presence mechanisms other photodissociation reactions. In this paper we construct phase space theory (PST) model triple fragmentation (3F) show that 3F...

Gas phase peroxyl radicals are central to our chemical understanding of combustion and atmospheric processes typically characterized by strong absorption in the UV (λmax ≈ 240 nm). The analogous maximum feature for arylperoxyl is predicted shift visible but has not previously been nor have any photoproducts arising from this transition identified. Here we describe controlled synthesis isolation vacuo an array charge-substituted phenylperoxyl at room temperature, including...

Understanding how neutral molecules become protonated during positive-ion electrospray ionization (ESI) mass spectrometry is critically important to ensure analytes can be efficiently ionized, detected, and unambiguously identified. The ESI solvent one of several parameters that alter the dominant site protonation in polyfunctional thus, turn, significantly change collision-induced dissociation (CID) spectra relied upon for compound identification. Ciprofloxacin─a common fluoroquinolone...

Abstract Targeting epigenetic mechanisms has shown promise against several cancers but so far been unsuccessful glioblastoma ( GBM ). Altered histone 3 lysine 4 methylation and increased lysine‐specific demethylase 1A LSD 1) expression in tumours nonetheless suggest that are involved . We engineered a dual‐action prodrug, which is activated by the high hydrogen peroxide levels associated with cells. This quinone methide phenylaminecyclopropane prodrug releases 1 inhibitor...

Abstract Although the deleterious effects of ozone on human respiratory system are well‐known, many precise chemical mechanisms that both cause damage and afford protection in pulmonary epithelial lining fluid poorly understood. As a key first step to elucidating intrinsic reactivity with proteins, its reactions deprotonated cysteine [Cys−H] − examined gas phase. Reaction proceeds at near collision limit give rich set products including 1) sequential oxygen atom abstraction yield sulfenate,...

Abstract Although the deleterious effects of ozone on human respiratory system are well‐known, many precise chemical mechanisms that both cause damage and afford protection in pulmonary epithelial lining fluid poorly understood. As a key first step to elucidating intrinsic reactivity with proteins, its reactions deprotonated cysteine [Cys−H] − examined gas phase. Reaction proceeds at near collision limit give rich set products including 1) sequential oxygen atom abstraction yield sulfenate,...