摘要:

AbstractSpider venom gland stores various glutaminergic blockers such as acylpolyamines, besides proteins and peptides. A method is described for structure determination of these acylpolyamines using fast‐atom bombardment and four‐sector tandem mass spectrometry. The collision‐induced dissociation (CID) spectra of protonated molecular ions of synthetic model compounds show only a small number of weak, sequence‐related product ions. But, unlike the CID spectra of [M + H]+ions, dissociation of sodium‐attached molecular ions leads to charge‐remote fragmentations and provides intense sequence‐related

ISSN:0951-4198    

DOI:10.1002/rcm.1290090502

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractThe mass spectrometry of an organometallic parasiticide used for treatment of leishmaniasis was studied using primarily fast‐atom bombardment with complementary studies conducted using electrospray ionization. The positive‐ion mass spectrum of meglumine antimonate contained ions with characteristic antimony isotope ratios (57:43) atm/z627/629, 507/509, 406/408 and 314/316. There was also evidence of ion clusters containing antimony atoms (Sb1–3), which decompose to the mass 507/509 species under acid pH conditions. For meglumine antimonate, an empirical formula C14H30O10N2Sb (molecular weight 507) is proposed with a structure containing four SbO bonds in a symmetrical g

ISSN:0951-4198    

DOI:10.1002/rcm.1290090503

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractPhoton emission from impacts of electrosprayed protein ions onto Au, Ta, Si and CsI surfaces was studied. Mass spectra of insulin, lysozyme and apo‐myoglobin were acquired by scanning the mass‐to‐charge ratio of a quadrupole mass filter while simultaneously detecting the photon and secondary electron signals. These spectra were very similar, but spectra acquired using photons displayed a somewhat better signal‐to‐noise ratio. The estimated photon emission yield is of the order of 0.5 photons per ion impact, a quantity which is not strongly dependent on target material. A higher yield of photons per incident ion was observed for apo‐myoglobin and lysozyme ions than for i

ISSN:0951-4198    

DOI:10.1002/rcm.1290090504

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractFragmentation of a natural Diels–Alder adduct, kuwanon G, has been examined using fast‐atom bombardment and collision‐induced dissociation (CID) techniques. The CID spectrum of a diene ion originating from aretro‐Diels–Alder cleavage of the [M + H]+ion gave an intense peak arising from the fragmentation of the diene moiety, as well as characteristic peaks arising from the fragmentation of a tautomeric 2,2‐dimethylpyran ring structure. The results obtained suggest that the diene can be irreversibly converted into the 2,2‐dimethylpyran ring structure under gas‐phase mass spectrome

ISSN:0951-4198    

DOI:10.1002/rcm.1290090505

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractThe problem of artefact peaks, in spectra obtained from various tandem mass spectrometric scans on instruments of both forward and reverse geometry, is examined. The filtering conditions imposed by additional analyzers are investigated, in order to evaluate the potential of several different triple sector geometries to reduce specific interferences. No previous evaluation of the rejection ability for artefacts of different origins has been presented with respect to the various geometries. In order to gain a better insight into the origin of various artefacts, and to more easily explain their occurrence in certain geometries, a new graphical representation was developed in order to take into account the effects of three analyzer fields. This approach allows different linked scans to be projected within a cube, while also qualitatively proposing an explanation for the presence or absence of artefact peaks. New scans can also be conceived by means of this method, as is the case with a new selected mass ion kinetic energy (SMIKE) scan, which allows artefacts present in MIKE scans performed using reverse geometry instruments to be determined.

ISSN:0951-4198    

DOI:10.1002/rcm.1290090506

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractThe combination of a membrane‐inlet system with an extra stage for the sorption of water has been achieved. The new device, used as an inlet system for a mass spectrometer, increases the sensitivity for the detection of organics in polar media such as water and broadens the range of substances that can be analyse

ISSN:0951-4198    

DOI:10.1002/rcm.1290090507

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractThe electron impact mass spectra of some benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐dicarboxylic acid dianilides and dithieno[3,2‐b:2′,3′‐d]thiophene‐2,6‐dicarboxylk acid dianilides are discussed. Dominant peaks in these dianilides are formed by the cleavage of a CN bond on one side of an anilino group. These ions fragment further by the cleavage of a CC bond on the other side of an anilino group and a CONRPhR′ group may be lost directly. After loss of CO, the characteristic benzodithiophene radical cation, C10H2S2Cl 2□ +., atm/z256 and the dithienothiophene radical cation, C8S3Cl 2□ +., atm/z262 are formed fr

ISSN:0951-4198    

DOI:10.1002/rcm.1290090508

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractPositive‐ion chemical ionization (CI) mass fragmentations were studied in the case of different 1,3‐dioxolanes. The formation in methane CI mass spectra of interesting fragment ions allowing the characterization of their parent carbonyl compounds and diols is discussed and some mechanisms (supported by D2O CI analyses) are proposed in order to explain these fragmentati

ISSN:0951-4198    

DOI:10.1002/rcm.1290090509

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractThe process of the detoxification of A‐destruxin into a polar linear peptidein vivoinLocusta migratoriahas been demonstrated using both high performance liquid chromatography and negative‐ion fast‐atom bombardment mass spectrometry. The final structure of the metabolite, after synthesis and comparison of retention time with the component in the crude biological mixture, was elucidated by positive‐ion fast‐atom bombardment linked‐scan mass spectrometry. Diagnostic fragment ions produced by collision‐induced dissociation

ISSN:0951-4198    

DOI:10.1002/rcm.1290090510

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY

摘要:

AbstractSeveral studies concerning the analysis and quantification of biological and pharmaceutical compounds have been effected during the past 20–30 years using different techniques of desorption‐ionization. In most cases, however, the authors have not been interested in the mass spectrometric fragmentation mechanisms of these products. Plasma desorption mass spectrometry (PDMS) is a powerful technique for analysing, without matrix interferences, solid biological and pharmaceutical compounds. In this work, we use PDMS in order to study the influence of the amine (amide) function on the fragmentation processes of nitrogen‐containing compounds. For this work, quaternary ammonium salts, trisubstituted amines, disubstituted amines and a compound with an amide function were chosen. Classical PD mass spectra, accurate mass measurements, transitions in the field free region (FFR), labelled compound spectra and thermodynamical data are reported for the structural study of these compounds. Our results allow us to propose fragmentation rules for positively charged nonfunctional biological nitrogen compounds. These rules relate to a class of structurally informative decomposition reactions that can be applied to the determination and of identification of structural unk

ISSN:0951-4198    

DOI:10.1002/rcm.1290090511

出版商:Heyden&Son Limited    

年代:1995

数据来源: WILEY