bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of impurities on the matrix‐assisted laser desorption/ionization mass spectra of insulin
Authors: Bajuk Anna , Głuch Krzysztof , Michalak Leszek 
Published: September 2002

AbstractThe effect of impurity (sodium sulfate Na2SO4; copper sulfate CuSO4; potassium ferrocyanide K4Fe(CN)6; and triammonium citrate (NH4)3C6H5O7) concentration on the positive matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) spectra of insulin is described. 2,5‐Dihydroxybenzoic acid was used as a desorption matrix. The estimated maximum concentrations of tested salts for which no insulin signal was observed were determined. Copyright © 2001 John Wiley & Sons, Ltd.
RSR13, a potential athletic performance enhancement agent: detection in urine by gas chromatography/mass spectrometry
Authors: Breidbach Andreas , Catlin Don H. 
Published: September 2002

AbstractRSR13 (2‐[4‐[[(3,5‐dimethylanilino)carbonyl]methyl]phenoxyl]‐2‐methylpropionic acid) is a synthetic allosteric modifier of hemoglobin that is currently in a phase III clinical trial as a radio‐enhancing agent. RSR13 has been shown to increase maximum oxygen uptake (VO2max) in a canine skeletal model, which makes it a potential performance‐enhancing agent for endurance athletes, since VO2max is an index of aerobic capacity. In this study we present a method for the detection of RSR13‐bis‐TMS in human urine by gas chromatography/electron impact ionization mass spectrometry (GC/EI‐MS) suitable for doping control laboratories. The presence of RSR13 is detected by monitoring the ions m/z 485 ([M]+·) and 470 ([M − CH3]+). The limit of detection (LOD) is less than 2 ng/mL in urine. Urine samples collected from clinical trial subjects immediately prior to receiving an infusion of RSR13 showed no evidence of RSR13, whereas post‐infusion urine samples contained up to 1181 µg/mL. A urine sample collected 36 h after administration of a small dose (10 mg/kg) and diluted 100‐fold showed a signal 80 times higher than the LOD. Urine samples obtained from 100 randomly selected athletes in our routine testing program did not show any traces of RSR13. Sport authorities may wish to add RSR13 to the list of prohibited substances. Copyright © 2001 John Wiley & Sons, Ltd.
Positive ion electrospray ionization mass spectrometry of double‐stranded DNA/drug complexes
Authors: Gupta Rajesh , Kapur Amit , Beck Jennifer L. , Sheil Margaret M. 
Published: September 2002

AbstractAn Erratum has been published for this article in Rapid Communicatons in Mass Spectrometry 16(7) 2002,740–741.Positive ion electrospray ionization mass spectra of 16 base‐pair double‐stranded (ds)DNA have been obtained with essentially no ions from single‐stranded DNA present. Single‐stranded DNA was minimized by: (1) careful choice of DNA sequences; (2) the use of a relatively high salt concentration (0.1 M ammonium acetate, pH 8.5), and, (3) a low desolvation temperature (40 °C). Similarly, ESI‐MS complexes of dsDNA with cisplatin, daunomycin and distamycin were obtained that contained only negligible amounts of single‐stranded DNA. The complexes with daunomycin and distamycin were more stable to strand separation in the gas phase than dsDNA alone. This is in agreement with solution studies and with other recent gas phase results. These data contrast with many earlier ESI‐MS studies of dsDNA and DNA/drug complexes in which ions from ssDNA are also normally observed. Copyright © 2001 John Wiley & Sons, Ltd.
18O Labeling: a tool for proteomics
Authors: Stewart Ian I , Thomson Ty , Figeys Daniel 
Published: September 2002

AbstractAn evaluation of the proteolytic labeling and quantification of proteins for diagnostic purposes using trypsin and 18O‐enriched H2O is presented. We demonstrate that comparative or relative quantitation can be performed effectively with this approach. We have developed a protocol that allows the conservation of the labeled peptides in natural abundance water without fear of back‐exchange providing that pH is sufficiently low to quench the catalytic activity of trypsin, but not so low as to promote chemical back‐exchange. Because the labeling efficiency depends on the nature of the peptide, a simple linear relationship between the relative 16O/18O digest buffer mixture content (x) and labeling efficiency (y) does not exist; rather it follows a probability based y = x2 relationship. As such, the extent of peptide labeling using 16O/18O digest buffer mixture ratios may deviate significantly from that expected based on a linear relationship. The evaluation of the relative Ziptip efficiency indicated a loss in sample recovery as the peptide concentration was reduced using normal conditions, suggesting that there is a limit below which there are diminishing returns. In addition, the adsorptive losses due to Speedvac dry down and recovery indicated modest (20%) losses that may vary widely (0–50%) from peptide to peptide. The in‐solution digestion efficiency of standard protein mixtures as a function of concentration revealed a linear decrease with decreasing concentration. This is consistent with enzyme kinetic effects and emphasizes a potential quantitation error that could arise when evaluating differential expression based on peptide detection. The results from our studies demonstrate the power of 18O labeling as an optimization tool for proteomics process development. Copyright © 2001 John Wiley & Sons, Ltd.
Electrospray mass spectrometry of hydrophobic compounds using dimethyl sulfoxide and dimethylformamide as solvents
Authors: Szabó Pál Tamás , Kele Zoltán 
Published: September 2002

AbstractThe use of dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) as solvents in electrospray ionization (ESI) is suggested for the analysis of hydrophobic compounds. Its use was shown to overcome solubility problems and resulted in good quality electrospray spectra of protected hydrophobic peptides, sugars and other hydrophobic compounds. Intense protonated and/or sodiated molecules were formed in positive ion mode while negative ion mode resulted in [M + 95]− ions from DMSO and [M + Cl]− ions from DMF in cases where no significant molecular ion related peaks could be observed applying commonly used protic solvents such as methanol or acetonitrile. Deuterium labeling (d6‐DMSO), high resolution experiments and tandem mass spectrometric measurements showed that the methanesulfonic acid (MSA), present in DMSO as a common impurity, is responsible for the formation of protonated molecules in positive ion mode and for methane sulfonate anion adducts [M + 95]− in negative ion mode. Copyright © 2001 John Wiley & Sons, Ltd.
Determination of hydroxyalkyl derivatives of cobalamin (vitamin B12) using reversed phase high performance liquid chromatography with electrospray tandem mass spectrometry and ultraviolet diode array detection
Authors: Alsberg Tomas , Minten Johanna , Haglund Johanna , Törnqvist Margareta 
Published: September 2002

AbstractElectrospray ionization tandem mass spectrometry (ESI‐MS/MS) and ultraviolet diode array detection (UV‐DAD), coupled on‐line to reversed phase high performance liquid chromatography (HPLC), was used for the characterization of hydroxyalkyl derivatives of cob(I)alamin. The reduced form of vitamin B12, cob(I)alamin, denoted a supernucleophile due to its high nucleophilic strength, has shown promise as an analytical tool in studies of electrophilically reactive compounds in vitro and in vivo. A method for analysis of DNA‐phosphate adducts was developed earlier utilizing the supernucleophilicity of cob(I)alamin to transfer alkyl groups from the phosphotriester configuration in DNA, with the formation of a Co‐substituted alkyl‐cobalamin (alkyl‐Cbl) complex. For the purpose of identification and quantification of alkyl‐Cbls at high sensitivity, an MS/MS method has been developed with application to a number of 2‐hydroxyalkyl‐cobalamins (OHalkyl‐Cbls). The precursor oxiranes were reacted with cob(I)alamin, followed by clean‐up and mass spectrometric analysis of the resulting OHalkyl‐Cbls. It was found that ionization was highly dependent on solvent composition. By using acetonitrile/water/trifluoroacetic acid (TFA) (eluent I), the base peak was the doubly protonated molecule [M + 2H]2+, whereas acetonitrile/water/1‐methylpiperidine (eluent II) yielded the singly protonated molecule [M + H]+ as the base peak. Excellent separation was obtained with eluent II, with good separation between stereoisomers, thus enabling the characterization of these by means of UV spectra. Limits of quantitation for 2‐hydroxypropyl‐cobalamin (OHPr‐Cbl) were 0.2 and 2 pg/µL (or 0.1 and 1 fmol/µL) using selected ion recording (SIR) with eluent I and II, respectively. The obtained detection level should be sufficient for analysis of alkyl‐Cbls from a wide range of toxicological applications. Copyright © 2001 John Wiley & Sons, Ltd.
Serum protein profiles of patients with pancreatic cancer and chronic pancreatitis: searching for a diagnostic protein pattern
Authors: Valerio A. , Basso D. , Mazza S. , Baldo G. , Tiengo A. , Pedrazzoli S. , Seraglia R. , Plebani M. 
Published: September 2002

AbstractIn this study, 13 sera from patients with pancreatic cancer, 9 from chronic pancreatitis and 10 from healthy subjects were analyzed by matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. The MALDI mass spectra revealed the presence of several low molecular weight peptides, among which some were detected only in the sera from both pathological conditions. On the other hand many peptides were observed only in control sera, and were absent in the sera from the two diseases. Therefore, MALDI analysis of the low molecular weight fraction (<10 000 Da) of sera from patients with pancreatic diseases enabled us to identify the presence of some disease‐related signals and also some signals characteristic of normal subjects. Copyright © 2001 John Wiley & Sons, Ltd.
A new method to determine the 17O isotopic abundance in CO2 using oxygen isotope exchange with a solid oxide
Authors: Assonov S.S. , Brenninkmeijer C. A. M. 
Published: September 2002

AbstractThis paper discusses a simple method to determine 17O isotope excess or deficiency (‘mass‐independent isotopic composition’) in CO2 gas. When applying conventional mass spectrometry of CO2 (m/z 44, 45 and 46) to determine the 17O/16O ratio, the 13C/12C ratio has to be established separately. This can be achieved by analysing an aliquot of sample CO2 before and after subjecting it to oxygen isotope exchange with a pool of oxygen with ‘normal’ 17O/16O ratio, i.e. with Δ17O≡δ17O−0.516 × δ18O = 0. Cerium oxide has been shown to be practically well suited for the exchange of CO2 oxygen; the reagent is safe and does not produce any contamination. The CO2‐CeO2 exchange reaction has 99.8 ± 0.7% recovery yield. At 650 °C this reaction reaches equilibrium in 30 min and, as tested, results in complete oxygen replacement. Δ17O determinations depend on accuracy of CO2 delta measurements: the repeatability of ±0.015‰ (1σ) in δ45R and δ46R deter‐mination relative to the working reference results in an error of Δ17O as small as ±0.33‰. Such a precision is sufficient for Δ17O determination in stratospheric CO2. The calculated Δ17O value systematically depends on absolute 17R and 13R ratios in isotopic reference materials, which are presently not yet known with certainty (the 17R value is most important), and may be inadequate for 17O‐correction with a = 0.516. Within the present uncertainty, Δ17O determined in 17O‐enriched CO2 agrees with the value directly measured in the enriched O2 from which this CO2 was produced. Besides Δ17O determination, investigated CO2‐CeO2 equilibration may have several other implications. Fast, complete isotopic exchange of CO2 by reaction with CeO2 may also be employed to get reproducible 17O‐correction and, hence, to better monitor small δ13C shifts and to isotopically equilibrate mixtures of CO2 gases. Copyright © 2001 John Wiley & Sons, Ltd.
Formation of binary alloy cluster ions from group‐14 elements and cobalt and comparison with solid‐state alloys
Authors: Zhang Xia , Li Guoliang , Xing Xiaopeng , Zhao Xiang , Tang Zichao , Gao Zhen 
Published: September 2002

AbstractBy using laser ablation on mixtures of transition metal cobalt and group‐14 elements, binary alloy cluster anions were produced while no binary alloy cluster cations were detected, and the homocluster cations of group‐14 elements appeared at very low abundance. The differences between clustering abilities of germanium, tin and lead with cobalt are described, and the chemical bonds in the binary alloy cluster anions appear to indicate a transition from covalent to metal bonds. The cluster anion [CoPb10]− appears in very high abundance (magic number), and an endohedral structure is proposed for this cluster. The cluster anion [CoPb12]−, also representing a magic number, probably has an icosahedral structure. Compared with solid‐state Co/Ge binary alloys, the compositions of most binary alloy cluster anions are germanium‐rich, in which the covalent bonds are predominant. Copyright © 2001 John Wiley & Sons, Ltd.
Determination of trace quaternary ammonium surfactants in water by combining solid‐phase extraction with surface‐assisted laser desorption/ionization mass spectrometry
Authors: Chen Yu‐Chie , Sun Mei‐Chuan 
Published: September 2002

AbstractThis study demonstrates the feasibility of combining solid‐phase extraction (SPE) with surface‐assisted laser desorption/ionization (SALDI) mass spectrometry to determine trace quaternary ammonium surfactants in water. The trace surfactants in water were directly concentrated on the surface of activated carbon sorbent in SPE. The activated carbon sorbent was then mixed with the SALDI liquid for SALDI analysis. No SPE elution procedure was necessary. Experimental results indicate that the surfactants with longer chain alkyl groups exhibit higher sensitivities than those with shorter chain alkyl groups in SPE‐SALDI analysis. The detection limit for hexadecyltrimethylammonium bromide is around 10 ppt in SPE‐SALDI analysis by sampling 100 mL of aqueous solution, while that of tetradecyltrimethylammonium bromide is about 100 ppt. The detection limit for decyltrimethylammonium bromide and dodecyltrimethylammonium bromide is in the low‐ppb range. Copyright © 2001 John Wiley & Sons, Ltd.
Electron ionisation induced fragmentation of ethyl 5(1H)‐oxo‐ and 7(1H)‐oxo‐1‐aryl‐2,3‐dihydroimidazo[1,2‐a]‐pyrimidine‐6‐carboxylates: evidence for an unusually regioselective rearrangement of M+• ions
Authors: Ovcharenko Vladimir V. , Pihlaja Kalevi , Matosiuk Dariusz 
Published: September 2002

AbstractThe 70‐eV electron ionisation (EI) mass spectra of the title compounds show clear differences between the 5‐oxo and 7‐oxo isomers due to regioselective fragmentations involving the ester function. Exceptionally abundant metastable peaks due to molecular ions fragmenting to [M −CO2]+· were observed exclusively for the 7‐oxo isomers, suggesting that the sufficiently long‐lived molecular ions undergo a slow rearrangement preceding this fragmentation reaction. The results are contrasted to the available literature data on the ester group fragmentations involving the loss of CO2 and the EI mass spectrometry of pyrimidone β‐oxo esters. A reaction mechanism is proposed for the elimination of CO2 following ethyl group migration to the pyrimidone carbonyl oxygen. Copyright © 2001 John Wiley & Sons, Ltd.
Determination of midazolam in human plasma by solid‐phase microextraction and gas chromatography/mass spectrometry
Authors: Frison Giampietro , Tedeschi Luciano , Maietti Sergio , Ferrara Santo Davide 
Published: September 2002

AbstractA new method is described for the qualitative and quantitative analysis of midazolam, a short‐acting 1,4‐imidazole benzodiazepine, in human plasma. It involves a plasma deproteinization step, solid‐phase microextraction (SPME) of midazolam using an 85‐µm polyacrylate fiber, and its detection by gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring (SIM) mode, using pinazepam as internal standard. The assay is linear over a midazolam plasma range of 1.5–300 ng/mL, relative intra‐ and inter‐assay standard deviations at 5 ng/mL are below 7%, and the limit of detection is 1 ng/mL. The method is simple, fast and sufficiently sensitive to be applied in clinical and forensic toxicology as well as for purposes of therapeutic drug monitoring. Copyright © 2001 John Wiley & Sons, Ltd.
Gas chromatography/mass spectrometry demonstration of steryl glycosides in eucalypt wood, Kraft pulp and process liquids
Authors: Gutiérrez Ana , del Río José C. 
Published: September 2002

AbstractThe occurrence of steryl glycosides (SG) and acyl steryl glycosides (ASG) in eucalypt (Eucalyptus globulus) wood has been investigated. These compounds were analyzed as their trimethylsilyl ethers by gas chromatography/mass spectrometry (GC/MS) using a 15 m length high‐temperature capillary column with a thin film, and identified on basis of their mass spectra and relative retention times comparing with those of authentic standards. Significant amounts of SG were identified in eucalypt wood whilst only traces of ASG could be detected. Eucalypt SG and ASG occur in the pyranoside form, which is readily distinguishable from the furanoside configuration by the mass spectra of their trimethylsilyl derivatives. The sterol part of the SG and ASG consisted of sitosterol, being sitosteryl 3β‐D‐glucopyranoside and sitosteryl (6′‐O‐palmitoyl)‐3β‐D‐glucopyranoside, the major SG and ASG found in E. globulus wood. The presence of SG and ASG was also investigated after kraft cooking by analyzing unbleached pulp and process water samples. The GC/MS results also revealed the presence of sitosteryl 3β‐D‐glucopyranoside in these samples. By contrast, no ASG could be detected. Therefore, we have shown that SG survive the kraft cooking and can be found at least partly intact after pulping, being a possible cause for pitch deposits together with free and esterified sterols. Copyright © 2001 John Wiley & Sons, Ltd.
Gas chromatography/combustion/isotope ratio mass spectrometry to control the misuse of androgens in breeding animals: new derivatisation method applied to testosterone metabolites and precursors in urine samples
Authors: Prévost Stéphanie , Nicol Tatiana , Monteau Fabrice , André François , Bizec Bruno Le 
Published: September 2002

AbstractA new derivatisation reaction applied to the analysis of steroids by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) was studied. The trimethylsilylated steroids were characterised by well‐resolved chromatographic signals, no peak tailing, reproducible 13C/12C measurements (0.32‰, n = 28), good signal‐to‐noise ratio and absolute intensity (5 × 10−9 A, 20 ng), and a slow degradation of copper oxide pellets in the combustion furnace. In addition, two new metabolites and one precursor of testosterone in bovine have been brought into consideration and used for GC/C/IRMS measurements, namely, 3β‐hydroxy‐5α‐androstan‐17‐one (epiandrosterone), 3β,17α‐dihydroxy‐5α‐androstane, and 3β,17α‐dihydroxy‐5‐androstene. The new findings have been applied to an elimination study in bovine of testosterone metabolites after an intramuscular injection of testosterone enanthate. Significant differences (up to 4‰) between testosterone metabolites and precursor were detectable at least three weeks after administration. Copyright © 2001 John Wiley & Sons, Ltd.
Atmospheric pressure chemical ionisation normal phase liquid chromatography mass spectrometry and tandem mass spectrometry of chlorophyll a allomers
Authors: Jie Chi , Walker J. Stuart , Keely Brendan J. 
Published: September 2002

AbstractFour oxidation products formed during the allomerisation reaction of chlorophyll a in methanol have been separated and identified using normal phase high‐performance liquid chromatography (NP‐HPLC) coupled with atmospheric pressure chemical ionisation (APCI) tandem mass spectrometry (MS/MS) and photodiode array detection. Fragmentation pathways of the main stereoisomers of the four major products, Mg‐purpurin‐7 dimethyl phytyl ester, 151‐MeO‐lact‐chl a, 132‐MeO‐chl a and 132‐HO‐chl a, have been assigned using APCI‐MSn aided by examination of deuteriated counterparts of the purpurin and the lactone. Diagnostic fragmentations have been determined, including those for Mg‐purpurin‐7 dimethyl phytyl ester and 151‐MeO‐lact‐chl a, which display very similar full MS and MS/MS spectra. The use of NP‐HPLC offers a rapid and efficient method which, combined with MS/MS, reduces reliance on precursor ion mass for assignment of structure in the allomerisation reaction where major and minor components are often isobaric. Copyright © 2002 John Wiley & Sons, Ltd.
Decentralized control of satellite formations
Authors: Russell Carpenter J. 
Published: September 2002

AbstractA decentralized architecture is proposed for autonomous establishment and maintenance of satellite formations. Such an architecture does not require a central supervisor, as the spacecraft can cooperatively track planned maneuvers and trajectories in the face of disturbances and uncertainties, while processing only local measurement information. If the planned maneuvers and trajectories are themselves optimal, the decentralized framework generates a neighbouring optimal control. Use of such a controller simplifies and improves the robustness of formation operations, since it distributes an autonomous capability for orbit determination and relative navigation, formation maintenance, and maneuver trim among all of the spacecraft. In an example formation flying scenario, the decentralized approach successfully maintains the formation in the face of uncertainties and nonlinear perturbations, and produces identical results to those of a corresponding centralized controller. Published in 2002 by John Wiley & Sons, Ltd.
Simulation‐based actuator selection for redundantly actuated robot mechanisms
Authors: Lee Yong‐Hoon , Han Youngmo , Iuraşcu Cornel C. , Park Frank C. 
Published: September 2002

AbstractThis article presents a simulation‐based strategy for sizing the actuators of a redundantly actuated robotic mechanism. The class of robotic mechanisms we consider may contain one or more closed loops and possess an arbitrary number of active and passive joints, and the number of actuators may exceed the mechanism's kinematic degrees of freedom. Our approach relies on a series of dynamic simulations of the mechanism, by applying Taguchi's method to systematically perform the simulations. To efficiently perform each of the dynamic simulations, we develop, using tools from modern screw theory, new recursive algorithms for the forward and inverse dynamics of the class of redundantly actuated mechanisms described. © 2002 Wiley Periodicals, Inc.