Mass Spectral Behavior Research Articles

Mechanistic and kinetic aspects of chemical ionization mass spectrometry of polynuclear aromatic hydrocarbons and their halogen-substituted analogues using oxidizing reagents: A gas chromatographic-mass spectrometric and Fourier transform mass spectrometric study

The mass spectral behavior of some substituted polynuclear aromatic hydrocarbons (PAHs) was investigated by using low-pressure chemical ionization conditions with a Fourier transform ion cyclotron resonance spectrometer (FT-MS) and by using gas chromatography-mass spectrometry (GC-MS) under higher pressure chemical ionization conditions. For the reactions of O −· with substituted PAHs, several reaction pathways are observed, including hydrogen atom transfer, hydrogen atom displacement, nucleophilic aromatic substitution, ring cleavage, and abstraction of H + 2 to generate (M - 2H) −. Bimolecular rate constants and product branching ratios for the reactions of O −· with benzene and a variety of substituted naphthalenes were obtained using FT-MS. The rate constants vary from (2.1 ± 0.4) × 10 −10 cm 3 molecule −1 s −1 for naphthalene to (2.1 ± 0.4) × 10 −9 cm 3 molecule −1 s −1 for 1 − chloronaphthalene, corresponding to reaction efficiencies of 8% and 60%, respectively. In contrast to previous pulsed radiolysis studies on the reactions of O −· with aromatic compounds in solution, O −· is observed to be a powerful gas-phase nucleophile. Nucleophilic substitution reactions are observed even in the absence of activating groups. Competition between this and other reaction pathways is related to the leaving-group abilities and inductive effects of the various substituents. Observation of reactions with the chlorinated naphthalenes implies limits on the heats of formation for the corresponding carbanions of Δ H f(1-ClC 10H − 6) < 46 ± 5 kcal mol −1 and Δ H f(2-ClC 10H − 6) < 49 ± 5 kcal mol −1 (1 kcal=4.184 kJ). Although the isomeric PAHs often give very similar mass spectra and their chromatographic peaks are not well resolved, differences in their GC-MS behavior can be used to distinguish anthracene and phenanthrene. For the unsubstituted PAHs reaction pathways are observed in agreement with recent studies and mass-selected FT-MS suggests which reaction pathways are due to ion-molecule reactions. Low ion intensities for many of the oxidation products relative to products formed by electron-transfer reactions of the PAHs suggest oxidation may occur by wall-catalyzed processes, in agreement with recent studies by Stemmler and Buchanan. The positional isomers of chloronaphthalene give clearly different mass spectra under both N 2O and N 2OO 2 chemical ionization conditions whereas the chloroanthracenes are not readily distinguished using GC-MS.

Gas chromatography/mass spectrometry of trimethylsilylated phenolic glucosides from roots ofUrtica dioica

A fraction of very polar compounds obtained from roots of Urtica dioica (stinging nettle) was converted into trimethylsilyl derivatives and subjected to gas chromatography. Mass spectra obtained from the single components indicated the presence of phenolic and other glucosides. Phenolic glucosides could be distinguished from alcoholic glucosides by their typical mass spectral fragmentation behaviour. A new type of phenolic glycerol ether glucosides is reported. Its structure was established by gas chromatography/mass spectrometry. The synthesis of one of the new ether aglycones is described.

Mass spectra of stereoisomers of 4-dimethylaminocyclohexanol derivatives.

The mass spectra of stereoisomers of five 4-dimethylaminocyclohexanol derivatives were recorded under electron ionization, and fragmentation patterns were elucidated by exact mass measurements and metastable ion analysis.The mass spectra showed differences in relative intensities of molecular ions between cis and trans isomers. The most characteristic feature of the mass spectral behavior of the compounds was fragmentation reaction, based on ionization of dimethylamino or hydroxyl groups.

A mass spectral analysis of some cucurbitacins isolated from Fevillea cordifolia

An examination of the mass spectral behaviour of cordifolin A 1(3β, 16α-dihydroxy-20, 25-epoxy-19(10→9β)abeo-10α-lanost-5-en-11, 22-dione), 3-O-β-D-glucopyranosyl-6, 1-β-D-glucopyranosidecordifolin A 2, 22α-hydroxy-23, 24-dehydrocordifolin A 3, and 22-deoxo-23, 24-dehydrocordifolin A 4, isolated from Fevillea cordifolia(Cucurbitaceae), illustrates the diagnostic fragmentation pathways that occur in these cucurbitacins. Tandem mass spectrometry allowed the construction of a detailed fragmentation map of 1. The structure elucidation of compounds 2–4 and their EI, Cl and FAB MS as well as those of cordifolin A 1 are discussed.

Gas chromatographic/mass spectrometric and tandem mass spectrometric investigations of synthetic amino acid conjugates of jasmonic acid and endogenously occurring related compounds fromVicia faba L

Some partial synthetic amino acid ((S)-alanine, (S)-leucine, (S)-isoleucine, (S)-aspartic acid, (S)-glutamic acid, (S)-phenylalanine, (S)- and (R)-valine) conjugates of the plant growth regulator (-)-jasmonic acid (JA) were investigated as methyl esters by capillary gas chromatography/mass spectrometry. By gas chromatographic data (retention indices) as well as by mass spectral behaviour all these substances can be differentiated unequivocally. In addition, the distinction between the leucine and isoleucine JA conjugates was carried out by mass-analysed ion kinetic energy spectroscopy (tandem mass spectrometry). Based on this some naturally occurring (S)-isoleucine conjugates of (-)-JA, (+)-7-iso-JA and related compounds as well as the (S)-leucine and (S)-phenylalanine conjugates of (-)-JA could be identified from extracts of the broad bean Vicia faba L.

Mass spectral study of differently substituted 2‐oxo‐ and 2‐thioxo‐1,3,4‐benzotriazepines

AbstractThe mass spectra of seven 2‐thioxo‐ and four 2‐oxo‐1,3,4‐benzotriazepines were recorded under electron ionization, and the fragmentation patterns were elucidated by exact mass measurement and metastable ion analysis. Some variations in the nature and position of the substituents greatly affected the mass spectra, allowing easy differentiation of isomeric compounds. The most characteristic feature of the mass spectral behavior of the compounds was the large number of ring contraction and complicated rearrangement reactions.

Mass spectral behaviour of some semisynthetic derivatives of vinblastine-type alkaloids

The mass spectral fragmentation of the biomedically important vinblastine (1a) and its eight semisynthetic derivatives obtained by selective oxidation have been studied using in-beam electron impact ionization, low and high resolution, as well as linked scanning techniques. The mass spectra were obtained without any thermal decomposition and exhibited abundant molecular ions and several fragment ions of structural importance. It was found that decomposition of these indole–indoline dimers having a velbanamine, or a ψ-aspidosperma, or a ψ-eburnane type indole moiety connected with the aspidosperma skeleton of vindoline (sets 1–3, respectively) led to several fragments of common types due mainly to the presence of the vindoline skeleton. However, sets 1–3 possessing various indole parts give rise to significant and characteristic fragments of these subunits, too. Varying the N(1) substituent of the vindoline part (CH3 H CHO), a strong influence was observed in the relative importance of the main reaction routes. It can be rationalized in terms of the effect of substituent on the localization of the positive charge.

Photolytic Properties of Ortho-Substituted 4-[N,N-Bis(β- Hydroxyethyl)amino]azobenzenes in Polymer Substrates

The synthesis of some novel derivatives of 4-[ N,N-bis(β-hydroxyethyl)- amino]azobenzene is reported, and the effects of ortho-substituents on photoinduced trans → cis isomerism about the azo group, mass spectral behavior, and the photost ability of these dyes are described. An ortho-nitro group inhibits trans → cis photo- isomerism about the azo group and affords poor photostability. Those ortho-substituted dyes showing a greater tendency to undergo photoinduced trans → cis isomerism and recover quickly are also more photostable and less subject to rupture at the β-nitrogen- carbon bond in the mass spectrometer. The photolysis experiments were done using acetate and triacetate film and fiber, and the mass spectrometric analyses were done by direct probe using the electron-impact technique.

Investigation of field desorption mass spectral behaviour of prostaglandins for their determination in biological fluids.

Field desorption (FD) mass spectrometry was applied to the determination of prostaglandin E2 (PGE2) in urine. Studies on synthetic compounds showed that methyl esters are stable under FD mass spectrometric conditions. The ester of PGE2 gives rise to protonated molecular ions and fragments due to the elimination of water and the side chains C8H14O and C8H12O2. This behaviour enabled its determination in the nanogram per millilitre range.

The gas-phase ion-molecule reaction of η 3-allyl-PtP(C 6H 5) 3Cl with SnCl 2+.

The electron impact (EI) mass spectral behaviour of η 3-C 3H 5PtP(C 6H 5) 3Cl ( 1) and η 3-C 3H 5PtP(C 6H 5) 3SnCl 3 ( 2) is described. The collisional spectra of 2 are compared with that of addition product obtained by the gas-phase ion-molecule reaction of 1 with SnCl 2 +.. The fragmentation pathway observed for both 2 and ( 1 + SnCl 2) suggests the existence of the pentacoordinate intermediate η3-C 3H 5PtP(C 6H 5) 3SnCl 2Cl.

Mass spectrometric behaviour of pentachlorophenyl β-carbonylenolate phosphino nickel(II) complexes: An example of thermal generation of a nickel(III) species

The mass spectral behaviour of pentachlorophenyl β-carbonylenolate phosphino nickel(II) square planar complexes has been investigated under electron impact (EI) and field desorption (FD) conditions. The fragmentation has been interpreted on the basis of the B/E linked scans and mass-analysed ion kinetic energy (MIKE) techniques. The acetylacetonate diphenylphosphino complex was found to undergo a solid state reaction in the probe, which led to the generation in situ of a nickel(III) chloro complex. Careful control of instrumental conditions and computer-assisted EI measurements made it possible to characterize the addition products as [NiCl(C 6Cl 5)(AcAc)PPh 2Me] and to propose a mechanism for its solid state generation.

Electron impact mass spectrometry of hemiterpenoid tricyclic quinoline alkaloids

AbstractThe mass spectral behaviour of some quinoline‐type alkaloids, 3,4‐dihydro‐2H,5H‐pyrano[3,2‐c]quinolin‐5‐ones, isomeric 3,4‐dihydro‐2H,5H‐pyrano[2,3‐b]quinolin‐5‐ones and 2H,5H‐pyrano[3,2‐c]quinolin‐5‐ones, was studied in detail with the aid of linked scans, exact mass measurements and collisional spectrometry. The occurrence of a partial isomerization of the differently annulated isomers to a common, open‐chain structure is discussed.

Mass spectroscopy of natural products. XXIII, Comparative positive and negative ion mass spectral studies of scapanin‐type diterpenoidst

AbstractThe mass spectral behaviour of 15 scapanin‐type diterpenoids (8α,12‐epoxylabdanes) was elucidated using accurate mass measurements and deuterium‐labelled derivatives. The results obtained allow a localization of the functional groups in the diterpenoid system. Furthermore, the negative ion mass spectra of the scapanin‐type diterpenoids are discussed and compared with the positive ion spectra.

Substituent effects on the mass spectral behavior of some N‐amino spirothiazolidinones

Substituent effects on the mass spectral behavior of some <i>N</i>‐amino spirothiazolidinones

Mass spectral behavior and HPLC of some unusual molecular phospholipid species

The molecular species of the major phospholipids from the marine sponges Parasperella psila and Microciona prolifera were studied using chemical hydrolysis, enzymatic degradation and capillary gas chromatography (GC), high performance liquid chromatography (HPLC), desorption chemical ionization (DCI), fast atom bombardment (FAB) combined with collisionally activated decomposition (CAD) mass spectrometry. Two new solvent systems were developed for the isolation of these species from the sponges. Our investigations indicated the existence of unusual symmetrical phospholipids as major components. 1,2-Di-(5 Z,9 Z)-5,9-hexacosadienoyl- sn-glycero-3-phosphoethanolamine was found in both organisms, while 1,2-di(5 Z,9 Z,19 Z)-5,9,19-hexacosatrienoyl- sn-glycero-3-phosphoethanolamine was present in M. prolifera. 1,2-Di-(4 Z,7 Z,10 Z,13 Z,16 Z,19 Z)4,7,10,13,16,19-docosahexaentoyl- sn-glycero-3-phosphocholine was the major molecular species in the PC fraction of M. prolifera.

Mass spectrometric studies of heterocyclic organophosphorus compounds: 1,3,2‐benzodioxaphospholes

AbstractThe mass spectral behaviour of a new type of organophosphorus compound, 1,3,2‐benzodioxaphospholes, under 70 eV electron impact has been studied by means of high and low resolution mass spectrometry as well as by B/E and B2/E linked scans. The influence of different substituents in the molecule (O, S or N) on the mass spectra is investigated. The reason for isomerization between oxygen and sulphur within a molecule studied by mass spectrometry is discussed.

Makrocyclische Benzolactone durch Ringerweiterung von 2‐Nitrocycloalkanonen

Macrocyclic Benzolactones by Ring Enlargement of 2‐NitrocycloalkanonesReaction of 2‐nitroalkanones with 1,4‐benzoquinone in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐en gave (hydroxybenzo)nitrolactones of general formula 6 (Scheme 1). The transformation involves a Michael reaction, aromatization, and ring enlargement via a five‐membered intermediate. The (hydroxybenzo)nitrolactones were converted to the already known (acetoxybenzo)oxolactones 15–17. The characteristic mass spectral behavior of the ring‐enlarged products is discussed.

Mass spectral studies of some rotenoid stereoisomers

AbstractThe mass spectral behaviour of several rotenoid stereoisomers is discussed.

Pmr and Mass Spectral Behaviour of 12a-Hydroxyrotenoids

Pmr and Mass Spectral Behaviour of 12a-Hydroxyrotenoids

Mass spectral analysis of perfluoroacylated derivatives of some arylalkylamines of biological interest

Numerous amines of biological interest can acetylated in aqueous solution, extracted and then perfluoroacylated for analysis by electron-capture gas chromatography. The structures of the products which are obtained can be confirmed by recording and interpreting their mass spectra. The electron impact mass spectral behaviour of various derivatized amines (amphetamine, ephedrine, p-hydroxyamphetamine, 3-methoxytyramine, norephedrine, normetanephrine, norpseudoephedrine, p-octopamine, 2-phenylethylamine, phenylethanolamine, pseudoephedrine, phentermine, m-tyramine and p-tyramine) is described.