bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid screening of genetic polymorphisms using buccal cell DNA with detection by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Liu Yan‐Hui , Bai Jian , Zhu Yongdong , Liang Xiaoli , Lubman David M. , Siemieniak David , Venta Patrick J. 
Published: May 2005

AbstractA new approach is developed for the rapid and cost‐effective detection of human genetic polymorphisms based on matrix‐assisted laser description/ionization mass spectrometric (MALDI MS) detection using a nitrocellulose film substrate. This method employs polymerase chain reaction (PCR) amplification using DNA extracted from buccal cells as templates, followed by direct digestion with restriction enzymes and subsequent analysis by MALDI MS. The extraction of DNA from buccal cells provides a rapid and convenient means for sampling PCR‐based diagnostic analysis. The amount of DNA was sufficient as the template for both normal PCR amplifications, and amplifications involving the use of mismatched primers and multiple primers. The MALDI MS methodology has been successfully used for the analysis of such PCR products where restriction fragments generated directly in PCR reactions have been used for detection of carbonic anhydrase and cystic fibrosis transmembrane conductance regulator as model genes. The detection of genetic polymorphisms following routine biological and clinical procedures with the MALDI MS method is demonstrated. The results from MALDI MS analysis are shown to be comparable to those obtained from gel electrophoresis but the MALDI MS method is several orders of magnitude faster than gel electrophoretic techniques. The method described herein should also be readily extended to other areas involving DNA screening and testing.
A tandem reflectron time‐of‐flight mass spectrometer for the investigation of laser photofragmentation of molecular ions
Authors: Jia W. J. , Ledingham K. W. D. , Scott C. T. J. , Kosmidis C. , Singhal R. P. 
Published: May 2005

AbstractA tandem reflectron time‐of‐flight mass spectrometer has been constructed for the investigation of laser photofragmentation of selected molecular ions. Ions are generated by an ablation laser and attracted by ion optics into the field‐free flight region of a reflectron time‐of‐flight mass spectrometer. Laser photofragmentation of selected molecular ions takes place at the turn‐around point of ions in the reflectron. Fragmentation mass calibration, parent ion selection, ion collection effects, reflectron field effects and the mass resolution of this tandem reflectron time‐of‐flight mass spectrometer are described. Furthermore it is shown that laser parameters may be used to control the fragmentation pattern.
Pyrolysis/gas chromatography/mass spectrometry of lignocellulose
Authors: Galletti Guido C. , Bocchini Paola 
Published: May 2005

AbstractThe use of pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) to determine the molecular composition of lignocellulose is reviewed and the technique illustrated with applications on some novel systems. Constituents and structural arrangement of lignocellulosic polymers in plant cell wall are briefly described. The basic principles of pyrolysis and the main advantages and disadvantages of PY/GC/MS are discussed. PY/GC/MS analyses of (a) paper industry effluents, (b) agricultural by‐products subjected to biological processes of delignification and (c) recycled paper are presented as examples of the amount of information that PY/GC/MS can provide on lignin classification and monitoring of delignification treatments as well as on the fingerprinting of lignocellulosic materials. The ion trap detector mass spectra of 56 pyrolysis products of lignocellulose, including compounds of phenolic, furanic and pyranic nature, are shown.
Enhancement of methylation analysis of complex carbohydrates using pyridine as reagent in chemical ionization mass spectrometry
Authors: Pätoprstý V. , Kováčik V. , Karácsonyi S. 
Published: May 2005

AbstractUnder the conditions of chemical ionization (CI) mass spectrometry, protonated pyridine [PyrH]+ and partially methylated alditol acetates (PMAAs) form very stable adducts. The CI mass spectra exhibit, exclusively, peaks due to quasimolecular [M + PyrH]+ adduct ions. The methylation analysis of complex carbohydrates can be enhanced by using the pyridine CI mass spectra to complement electron impact mass spectra and gas chromatography data. As a result, the sensitivity as well as the accuracy of quantitative analysis of PMMA components is increased.
Modified ionspray interface for supercritical fluid chromatography/mass spectrometry: Interface design and initial results
Authors: Pinkston J. David , Baker Timothy R. 
Published: May 2005

AbstractA pneumatically assisted electrospray liquid chromatography/mass spectrometry interface has been modified for use with open‐tubular supercritical fluid chromatography (SFC). The modified interface houses the SFC flow restrictor within the spray device. A sheath‐flow liquid of methanol or methanol/water containing ammonium acetate flows coaxially to the restrictor. The addition of the sheath‐flow liquid results in the ionization of analytes known to be in a neutral charge state during the chromatographic separation. The sheath‐flow liquid also allows for the independent operation of the chromatograph and the mass spectrometer. Both could be operated under optimum conditions. The operation of the interface was optimized using a solution of poly(dimethylsiloxane) in CO2 introduced by continuous infusion. We also report the application of the modified instrument to samples containing amines and propoxylated alcohols.
Quantification of polyphosphoinositides using selected ion monitoring electrospray mass spectrometry
Authors: Michelsen Peter , Jergil Bengt , Odham Göran 
Published: May 2005

AbstractPolyphosphoinositides (PIP) and (PIP2) show prominent negative singly and doubly charged deprotonated molecules in electrospray mass spectrometry. These ions can be used for quantification of PIP and PIP2 in the low picomole range, without prior chromatographic separation, using selected ion monitoring and consecutive measurements of the signals from the deprotonated singly charged molecules. The dose response curves for both compounds are linear. In a complex matrix consisting of polar lipids (Folch extract) PIP and PIP2 monitored at m/z 965.4 and 1045.5 (stearoyl and arachidonoyl) were determined in the low picomole range, at a flow rate of 100 μL/min. Collision‐induced decomposition of PIP and PIP2 using a mixture of xenon and argon at 25 eV afforded identical high mass ions formed by loss of a molecule of water from PIP and a phosphate group and a molecule of water from PIP2. The results indicate that polyphosphoinositides, and biologically relevant changes in their concentrations, can be quantified directly in cells and cellular membranes by selected‐ion monitoring with electrospray mass spectrometry.
Application of the fast‐evaporation sample preparation method for improving quantification of angiotensin II by matrix‐assisted laser desorption/ionization
Authors: Nicola Anthony J. , Gusev Arkady I. , Proctor Andrew , Jackson Edwin K. , Hercules David M. 
Published: May 2005

AbstractThe fast‐evaporation method of sample preparation has been applied for quantitative analysis using matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. An instrumental protocol focusing on improvement of shot‐to‐shot repeatability and compensation for signal degradation has been developed for quantification of angiotensin II using the fast‐evaporation technique and an internal standard. The fast‐evaporation method was compared to the standard method of sample preparation (using a multicomponent matrix) in the quantitative analysis of angiotensin II, and found to be superior in several respects. Improvement in sample homogeneity using the fast‐evaporation method enhanced both point‐to‐point repeatibility and sample‐to‐sample reproducibility. The relative standard deviations of the analyte/internal standard ratios (point RSD) were decreased by a factor of three compared to those obtained using the multicomponent matrix method. The average point RSD was found to be ca. 5% for the fast‐evaporation technique. Two internal standards were evaluated for quantification of angiotensin II. The better one, 1‐SAR‐8‐Ile angiotensin II, yielded a relative standard deviation of the standard curve slope of ca. 2.2% over two orders of magnitude of concentration (45 nM to 3000 nM), an improvement by a factor of two over the standard preparation method. Renal microdialysate samples, spiked with angiotensin II and the internal standard 1‐SAR‐8‐Ile angiotensin II, were also analyzed using the fast‐evaporation technique. The detection limit was calculated to be in the high attomole range (675amol). Furthermore, the accuracy for a single determination of angiotensin II concentration in these samples was found to be 13.9% with a relative error of 8.19%.
The role of ion–neutral reorientation in the unimolecular reactivity of e‐ionized amines. The influence of the size of the fragments
Authors: Longevialle Pierre 
Published: May 2005

AbstractDuring the unimolecular decomposition of an ion IN→I(ion) + N(neutral), the fragments may mutually reorient before decomposition, when the energy has reached the reorientation critical energy. After I‐N reorientation, I and N have only a very low probability of recombining into the original IN structure, but can only decompose (or occasionally follow a different reaction pathway, if thermochemically allowed). As a consequence, decompositions of metastable ions are irreversibly decided as soon as their corresponding I‐N reorientation threshold has been reached. It is shown, from the mass‐analysed ion kinetic energy of several series of homologous primary amines, that the competition between α‐cleavages (and the occasionally accompanying losses of alkanes) is governed by the relative I‐N reorientation–(rather than decomposition)–critical energies.When the neutral has no permanent dipole, the I‐N reorientation critical energy depends on the sizes of the fragments, especially that of the fragment ion. An interpretation is proposed related to the McAdoo and Hudson hypothesis.27
High temperature mass spectrometric study of the B2O3Al2O3 system at 1248–1850 K
Authors: Stolyarova V. L. , Shilov A. L. , Ivanov G. G. , Shultz M. M. , Seetharaman S. 
Published: May 2005

AbstractThe high‐temperature mass spectrometric Knudsen effusion method has been used to study the vaporization processes and thermodynamic properties of the B2O3Al2O3 system in the temperature range 1248–1850 K. Data on the B2O3 partial vapour pressures and the B2O3 activities in the system under consideration were obtained. The enthalpies of formation of Al4B2O9 and Al18B4O33 have been evaluated from the values of the enthalpies of B2O3 sublimation from boron oxide and from these compounds. Comparison is made between the available phase diagram of the B2O3Al2O3 system and the results obtained in the present study, using the complete isothermal vaporization method.
Pyrolysis gas chromatography/mass spectrometry used to simultaneously determine essential oil and phenolic compounds in the monks' pepper vitex agnus‐castus L
Authors: Galletti Guido C. , Russo Maria Teresa , Bocchini Paola 
Published: May 2005

AbstractPyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) was used as a microtechnique for the simultaneous analysis of various classes of compounds in leaves and berries of Vitex agnus‐castus L. (Verbenaceae) plants growing wild in Calabria. Terpene and sesquiterpene hydrocarbons from the essential‐oil fraction, simple phenolics, tentatively ascribed to moieties of flavonoids and glucosides, and free and esterified fatty acids were determined. Aliquots in the milligram range of plant material were assayed as such with no extraction or use of different analytical techniques for the different chemical classes under investigation. White the terpene and sesquiterpene yields remained practically constant over the entire range of pyrolysis temperatures examined, i.e. 200–900 °C, phenolics appeared at a pyrolysis temperature of 300 °C and reached a maximum at 700–900 °C. Pyrolysis in the presence of tetramethylammonium hydroxide was carried out in order to perform the so‐called thermally assisted hydrolysis methylation/gas chromatography/mass spectrometry (THM/GC/MS) and analyse more polar compounds, such as fatty acids, as their methylated derivatives.
Determination of artefact peaks in mass‐analysed ion kinetic energy spectra using a new linked scan for ebe geometry magnetic sector instruments
Authors: Mouget Yves , Bertrand Michel J. 
Published: May 2005

AbstractThe possible presence of artefact peaks in mass‐analyzed ion kinetic energy (MIKE) spectra has been recognized when such scans are performed using a two‐sector instrument of reverse (BE) configuration. Since the presence of an artefact peak can be misleading when interpreting a spectrum, a new scan is proposed which allows these artefacts to be identified. This scan involves linking and scanning the two electrostatic sectors of an E1BE2 geometry instrument, while maintaining the magnet at the mass selected for the MIKE scan. This selected mass‐analyzed ion kinetic energy (SMIKE) scan at E1=E2 results in a spectrum containing only artefact peaks that can be present in the corresponding MIKE spectrum.
Revisit of MALDI for small proteins
Authors: Zhu Y. F. , Lee K. L. , Tang K. , Allman S. L. , Taranenko N. I. , Chen C. H. 
Published: May 2005

AbstractMatrix‐assisted laser desorption/ionization (MALDI) was used for several small proteins (such as insulin) and for peptides. It was found that the detection efficiencies of MALDI for the insulin B chain and the insulin A chain are drastically different. Similar phenomena were also observed for various types of peptides. The positive‐ion signal of MALDI in detecting proteins or peptides was found to be greatly enhanced by the presence of a basic amino acid in their chains. The experimental results indicate that this enhancement may arise from proton transfer in solution by an acid‐base reaction between the protein/peptide and matrix molecule. This pre‐protonated mechanism provides a low energy barrier for the ionization of peptides in a MALDI process, and greatly reduces the energy threshold of MALDI. Matrix effects on the ionization mechanism are discussed.
Liquid secondary‐ion mass spectrometry of peptides containing multiple tyrosine‐O‐sulfates
Authors: Yagami Takeshi , Kitagawa Kouki , Futaki Shiroh 
Published: May 2005

AbstractThe behavior of peptides containing multiple tyrosine‐O‐sulfates in liquid secondary‐ion mass spectrometry (LSIMS) has been investigated. In the positive‐ion spectra of the peptides containing two tyrosine‐O‐sulfates, Cionin and CCK‐associated C‐terminal nonapeptide (CAP‐9), the completely desulfated [M+H−2SO3]+ ions formed the base peaks, accompanying the significantly less‐intense [M+H]+ and [M+H−SO3]+ ions. In the negative‐ion spectra of these peptides, the [M−H]− and [M−H−SO3]− ions gave prominent peaks with significantly weaker [M−H−2SO3]− ions. In the case of a peptide containing three tyrosine‐O‐sulfates, [Tyr(SO3H)1]CAP‐9, the completely desulfated [M+H−3SO3]+ ion again formed the base peak in the positive‐ion spectrum. On the other hand, the sulfated tyrosine‐containing [M+H]+, [M+H−SO3]+, and [M+H−2SO3]+ ions were of negligible abundance compared to the spectra of peptides containing two tyrosine‐O‐sulfates. We observed an intriguing ‘ladder fragmentation pattern’ in the negative‐ion spectrum of this triply‐sulfated peptide. The ladder consisted of the [M−H]−, [M−H−SO3]−, and [M−H−2SO3]− ions, but without the completely desulfated [M−H−3SO3]− ion. These characteristic fragmentation patterns of sulfated tyrosine‐containing peptides were considered to bear a close correlation with the inherent acid‐lability of a tyrosine‐O‐sulfate in solution. A possible mechanism has been proposed to explain the fragmentation patterns in the gaseous phase, in which a proton plays a decisive role.
Collisionally‐activated dissociation spectra of linear peptides in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Kosaka T. , Ishikawa T. , Kinoshita T. 
Published: May 2005

AbstractCollisionally‐activated dissociation (CAD) studies of linear peptides were performed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. Four different gases, viz. helium, nitrogen, argon and xenon, were introduced into a gas cell, installed close to the ion source of TOF mass spectrometer, to obtain high‐energy CAD information. The CAD spectral patterns for the linear peptides obtained using the four gases were almost the same as each other. The fragments characteristically obtained in conventional high‐energy CAD using tandem mass spectrometry were observed also in these spectra. A difference between CAD spectra and post‐source decay product‐ion spectra has been demonstrated.
Determination of the pesticides diflubenzuron and clofentezine in plums, strawberries and blackcurrant‐based fruit drinks by high performance liquid chromatographic/atmospheric pressure chemical ionization‐mass spectrometry
Authors: Barnes Karen A. , Fussell Richard J. , Startin James R. , Thorpe Stephen A. , Reynolds Stewart L. 
Published: May 2005

AbstractA high performance liquid chromatographic/atmospheric pressure chemical ionization‐mass spectrometric (HPLC/APCI‐MS) method has been developed for the determination of the pesticides diflubenzuron (1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl)urea) and clofentezine (3,6‐bis(2‐chlorophenyl)‐1,2,4,5‐tetrazine) in plums, strawberries and blackcurrant‐based fruit drinks. Samples were homogenized with acetone, extracted into dichloromethane + cyclohexane and cleaned‐up by high performance gel permeation chromatography. HPLC was performed on an ODS column with methanol + water at 1 mL/min. Detection was by negative‐ion selected‐ion monitoring APCI‐MS. Comparison of response with solvent and matrix‐matched standards showed some ehancement of response for the latter, and these standards were consequently used for quantification. The calibration was linear over the range 0.05–0.50 ng/μL in all three matrices. The mean overall recovery of diflubenzuron and clofentezine from spiked extracts (0.086 mg/kg) in all three matrices was 76% and 70% respectively with relative standard deviations of 15% and 12% respectively (n = 12). The limit of detection was both compound and commodity dependent and ranged from 0.01–0.05 ng/μL, equivalent to 0.003–0.014 mg/kg in the crop.
Identification of urinary and biliary conjugated metabolites of the neuromuscular blocker 51w89 by liquid chromatography/mass spectrometry
Authors: Dear Gordon J. , Jones Anne E. , Pleasance Stephen , Harrelson Jane C. , Johnson Thomas E. 
Published: May 2005

AbstractCisatracurium, (1R, 1′R, 2R, 2′R)‐2,2‐[1,5‐pentanediylbis‐[oxy(3‐oxo‐3,1‐propanediyl)]]bis[1‐[(3,4‐dimethoxy‐phenyl)‐methyl]‐1,2,3,4‐tetrahydro‐6,7‐dimethoxy‐2‐methylisoquinolinium] dibenzenesulphonate (51W89), is an intermediate‐acting neuromuscular blocking agent. 51W89 is one of ten isomers contained in Tracrium® (atracurium besylate) and represents' approximately 15 percent of the atracurium mixture. Clinical studies have indicated that 51W89 is more potent and is significantly weaker as a histamine releaser than atracurium. In vitro studies in human plasma have shown that, like atracurium, 51W89 spontaneously degrades at physiological pH by Hoffmann elimination to form laudanosine and the quaternary monoacrylate. Subsequent ester hydrolysis of the monoacrylate generates the monoquaternary alcohol. In rat plasma, 51W89 is also metabolized by non‐specific carboxylesterases to the monoquaternary alcohol and the monoquaternary acid, the former being rapidly hydrolysed further to the more stable acid. It has been reported that laudanosine can be further metabolized via N‐demethylation to yield tetrahydropapaverine. The rate‐limiting step in the degradation of 51W89 in human plasma is Hofmann elimination, whilst in rat plasma, the action of non‐specific carboxylesterases is rate limiting. As part of the development of 51W89, the disposition of 14C‐51W89 following a single intravenous bolus dose was studied in various animal species and humans. In the present work, we describe the identification of 51W89 metabolites in urine and bite from these studies by high performance liquid chromatography/mass spectrometry using pneumatically‐assisted electrospray ionization coupled to an on‐line radioactivity monitor. This methodology enabled rapid and sensitive screening of biological samples with minimal sample preparation. Structural confirmation of metabolites was obtained by tandem mass spectrometry. In addition to the expected metabolites, a number of urinary and biliary O‐glucuronic acid conjugate of monodesmethyl laudanosine and monodesmethyl tetrahdropapaverine were identified, which cochromatographed with an early eluting ‘unknown’ in the radioprofile. A sulphate conjugate of monodesmethyl laudanosine was also identified in cat bile. The characterization of these metabolites was assisted by the incorporation of on‐line radioactivity monitoring during mass spectroscopic analysis, which provided an invaluable means to distinguish drug‐related and endogenous material.
Charge‐remote fragmentation of ecdysteroids conjugated with phosphoric acid
Authors: Ikeda Midori , Fujita Tsuyoshi , Naoki Hideo , Naya Yoko , Mamiya Yoshitaka , Kamba Mari , Sonobe Haruyuki 
Published: May 2005

AbstractSuccessful application of tandem mass spectrometry on a series of the ecdysteroid phosphates (eddysteroids conjugated with phosphoric acid) led to general information for their characterization. The 22‐phosphates and the 2‐(or 3‐)phosphates can be definitely distinguished by their charge‐remote fragmentation patterns. In the case of the 22‐phosphates, information about the side‐chain moiety is readily obtained. In the case of the 2‐(or 3‐)phosphates, information about the ring as well as the side‐chain is readily available. Neither the positional isomers (2‐ and 3‐phosphates) in the A‐ring nor the configurational isomers (α and β) can be distinguished.
Molecular mass measurement of polymerase chain reaction products amplified from human blood dna by electrospray ionization mass spectrometry
Authors: Naito Yasuhiro , Ishikawa Keiichiro , Koga Yoshinori , Tsuneyoshi Toshihiro , Terunuma Hideya , Arakawa Ryuichi 
Published: May 2005

AbstractWe report here on the first analysis of polymerase chain reaction (PCR) products amplified from a small amount of human blood DNA by electrospray ionization mass spectrometry (ESI‐MS). Adenomatous polyposis coli (APC) gene fragment of about 50 base pairs (bp) with a relative molecular mass (Mr) of approximately 15 000 u was amplified from human blood DNA by PCR. The accurate molecular mass of the PCR products was determined with an accuracy of ∼0.005% by ESI‐MS. The amount of DNA used was only 100 ng (∼ 50 zmol; the theoretically required amount of blood is therefore less than 1 μL for PCR). The ESI‐MS measurement of the PCR products proved to be a new accurate, sensitive and fast tool for gene diagnosis.
Capillary zone electrophoresis/electrospray ionization mass spectrométry for the characterization of drugs of forensic interest
Authors: Curcuruto Ornella , Zaramella Alessio , Hamdan Mahmoud , Turrina Stefania , Tagliaro Franco 
Published: May 2005

AbstractSolutions containing between six and thirteen drug substances of forensic interest have been examined by capillary zone electrophoresis/electrospray mass spectrometry (CZE/ES‐MS). The effects of citrate buffer concentration and its content of organic modifiers on the migration time, resolution and migration order of the various components were assessed. Performing CZE/ES‐MS in full‐scan mode at elevated cone (skimmer) voltage allowed differentiation between nalorphine and thebaine which have isomeric structures.