bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solid‐phase microextraction gas chromatography/ion trap mass spectrometry and multistage mass spectrometry experiments in the characterization of germacrene D
Authors: Gioacchini A. M. , Menotta M. , Polidori E. , Giomaro G. , Stocchi V. 
Published: December 2002

AbstractGermacrene D is a vegetable pheromone utilized in interactions among organisms belonging to different species. For the first time, using solid‐phase microextraction/gas chromatography/ion trap mass spectrometry, the presence of this compound was detected in an in vitro mycorrhizal synthesis system where the mycelium of the ectomycorrhizal fungus Tuber borchii Vittad. interacts with the plant Tilia Americana L. From this symbiosis, a new structure, called ectomycorrhiza, is formed where the two symbionts exchange nutrients and metabolites. It seems that only after this interaction can the mycelium develop the fruitbody, commonly known as truffle. The results obtained allowed us to ascertain that germacrene D was synthesized by the plant exclusively in the presence of T. borchii. The originality of these data prompted us to hypothesize that this compound could be involved in the first step of ectomycorrhiza formation, as it is able to stimulate specific fungi receptors. In fact, plants release hundreds of secondary metabolites that are important in their interactions with other organisms. Copyright © 2002 John Wiley & Sons, Ltd.
Mass spectrometric investigation of gallium and zirconium complexes with octaethylporphyrin and tetraphenylporphyrin
Authors: Witowska‐Jarosz Janina , Górski Łukasz , Malinowska Elźbieta , Jarosz Maciej 
Published: December 2002

AbstractGallium and zirconium octaethylporphyrin (OEP) and tetraphenylporphyrin (TPP) were examined by electrospray ionization (ESI) mass spectrometry. All systems were prepared in dichloromethane with addition of a stabilizing lipophilic anionic agent, sodium tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate (NaTFPB). In the solutions examined both monomeric and dimeric metalloporphyrins were observed. In the gallium‐OEP mass spectrum the ion registered at m/z 601 was attributed to monomeric [Ga(OEP)]+ and that at m/z 1219 to the dimeric form, [{Ga(OEP)}2OH]+. Peaks appearing in the ESI mass spectra of zirconium systems were substantially less intense, probably owing to the relatively low stability of complexes of this metal caused by its different geometry preferences. The most abundant monomeric zirconium‐OEP complexes were [{Zr(OEP)OH}]+ (m/z 639) and [Zr(OEP)Cl]+ (m/z 657), and dimeric [{Zr(OEP)OH}2]2+ (m/z 639). Analogous species were observed in the Zr(TPP) system: monomeric [{Zr(OEP)OH}]+ (m/z 719) and [Zr(TPP)Cl]+ (m/z 737) and dimeric [{Zr(TPP)OH}2]2+ (m/z 719). In both cases series of other dimers, e.g. [{Zr(OEP)}2O2H]+ (m/z 1277), [{Zr(OEP)OH}2Cl]+ (m/z 1313), [Zr(TPP)2O2H]+, (m/z 1437), [{Zr(TPP)OH}2OH]+ (m/z 1455) and [{Zr(TPP)OH}2Cl]+ (m/z 1473), appeared. The results obtained confirmed the hypothesis concerning the formation of dimeric metalloporphyrins in solutions containing stabilizing lipophilic anions. It also allowed us to explain the super‐Nernstian slopes of the calibration curves towards primary anions of ion‐selective electrodes with membranes containing the examined metalloporphyrins. Copyright © 2002 John Wiley & Sons, Ltd.
Analyses of gas composition in vacuum systems by mass spectrometry
Authors: Řepa P. , Tesař J. , Gronych T. , Peksa L. , Wild J. 
Published: December 2002

AbstractAnalyses of the composition of residual gases for diagnostic purposes, analyses of the atmosphere enforced by the introduction of gases for technological purposes and analyses of gases released from analyte materials in numerous analytical methods (e.g. TSD, SIMS) are frequently carried out in vacuum systems. There is only a small amount of gas available, in the vacuum system so the most important property of a mass spectrometer is high sensitivity. As a consequence, the mass resolution is usually low. Moreover, a low outgassing rate of the mass spectrometer itself and all parts connecting it to the vacuum system is required. Dynamic mass spectrometry satisfies these demands best. Quadrupole mass spectrometers are almost solely utilized in applications, although the time‐of‐flight mass spectrometer has come into use recently. The main disadvantage of the quadrupole mass spectrometer is a strong dependence of the sensitivity and the mass discrimination factor on the stability of the supply voltages. Together with the necessity to use multipliers for detection of the ion current, this leads to a requirement for frequent recalibration. Another serious problem, that is met in such applications is the estimation of the gas composition from the measured mass spectra. Usually, the analyte gas mixtures consist of various individual gases, or at least are measured on a background of such mixtures. This implies a requirement for the exact knowledge of the fragmentation pattern of the gases, and again the necessity for frequent calibration over a satisfactorily wide range of mass numbers. Some theoretical considerations and some experimental results obtained by the authors are presented. Copyright © 2002 John Wiley & Sons, Ltd.
Atmospheric pressure ionization mass spectrometry of purine and pyrimidine markers of inherited metabolic disorders
Authors: Fryčák Petr , Hušková Renata , Adam Tomáš , Lemr Karel 
Published: December 2002

AbstractPurines and pyrimidines are of interest owing to their significance in processes in living organisms. Mass spectrometry is a promising analytical tool utilized in their analysis. Two atmospheric pressure ionization (API) methods (electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)) in both negative and positive modes applied to selected purine and pyrimidine metabolites (markers of inherited metabolic disorders) were studied. APCI is less sensitive to alkali metal cations present in a sample and offers higher response than ESI for studied compounds. Both of the techniques afford quasi‐molecular ions, but fragmentation also occurs to a certain extent. However, the application of collision‐induced dissociation of quasi‐molecular ions is essential to confirm a certain metabolite in a sample. Fragmentation of both positive and negative ions was evaluated using multi‐stage mass spectrometric experiments. Typical neutral losses correspond to molecules NH3, H2O, HCN, CO, H2NCN, HNCO and CO2. The ion [NCO]− arises in the negative mode. The cleavage of the glycosidic C—N bond is characteristic for relevant metabolites. Other neutral losses (CH2O, C2H4O2 and C3H6O3) originate from fragmentation of the glycosidic part of the molecules. In addition to fragmentation, the formation of adducts of some ions with applied solvents (H2O, CH3OH) was observed. The composition of the solution infused into the ion source affects the appearance of the mass spectra. Tandem mass spectra allow one to distinguish compounds with the same molecular mass (uridine–pseudouridine and adenosine–2'‐deoxyguanosine). Flow injection analysis APCI‐MS/MS was tested on model samples of human urines corresponding to adenosine deaminase deficiency and xanthine oxidase deficiency. In both cases, the results showed potential diagnostic usefulness. Copyright © 2002 John Wiley & Sons, Ltd.
Development of a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and saccharidic compounds in atmospheric aerosols. Application to urban aerosols
Authors: Pashynska Vlada , Vermeylen Reinhilde , Vas Gyorgy , Maenhaut Willy , Claeys Magda 
Published: December 2002

AbstractWe developed and validated a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and the related monosaccharide anhydrides, mannosan, galactosan and 1,6‐anhydro‐β‐D‐glucofuranose in urban atmospheric aerosols collected on quartz fiber filters. The method is based on extraction with dichloromethane–methanol (80 : 20, v/v), trimethylsilylation, multiple reaction monitoring in the tandem mass spectrometric mode using the ion at m/z 217, and the use of an internal standard calibration procedure with the structurally related compound methyl β‐L‐arabinopyranoside. In addition, the method allows the quantification of other saccharidic compounds, arabitol, mannitol, glucose, fructose, inositol and sucrose, which were found to be important in summer aerosols. The recovery of levoglucosan was estimated by spiking blank filters and was better than 90%. The precision evaluated by analyzing parts of the same filters was about 2% for the monosaccharide anhydrides and 7% for the other saccharidic compounds in the case of a winter aerosol sample, and the corresponding values for a summer aerosol sample were 5% and 8%. The method was applied to urban PM10 (particulate matter of <10 µm aerodynamic diameter) aerosols collected at Ghent, Belgium, during a 2000–2001 winter and a 2001 summer episode and revealed interesting seasonal variations. While monosaccharide anhydrides were relatively more important during the winter season owing to wood burning, the other saccharidic compounds were more prevalent during the summer season, with some of them, if not all, originating from the vegetation. Copyright © 2002 John Wiley & Sons, Ltd.
An unusual rearrangement of Zofenopril, a new ACE inhibitor drug: mass spectrometric and conformational studies
Authors: Cartoni Antonella , Altamura Maria , Animati Fabio , Balacco Giuseppe , Cosi Riccardo , Ettorre Alessandro , Madami Andrea , Triolo Antonio 
Published: December 2002

AbstractZofenopril (1) is a new ACE inhibitor, used in therapy for hypertension and post‐myocardial infarction. The protonated quasi‐molecular ion (m/z 430) of 1, obtained under positive electrospray ionization conditions, loses a benzoic acid molecule (m/z 308), which in turn decomposes via loss of CO (m/z 280) when low‐energy collisional‐induced dissociation (CID) and in‐source experiments are performed. This rearrangement is the main fragmentation process and can be observed both in‐source and in the product ion tandem mass spectra, using either an ion trap or a triple quadrupole instrument.Other known diastereoisomers of 1, an impurity with an acetyl in the place of the benzoyl group (2) and an impurity with two propanoyl chains in series (3), give the same rearrangement. On the other hand, the mass spectra of the methyl ester (4) and an impurity with two proline moieties (5) do not show this unusual fragmentation. Time‐resolved CID spectra of 1 show that the rearrangement occurs after about 2 ms, a time scale comparable to those of the other non‐rearrangement cleavages. These experiments suggest a conformation in the gas phase for 1 in which the benzoyl group is close to the hydroxyl of the carboxylic acid group, from which the rearrangement could readily occur. Since compounds 4 and 5 do not show the same behaviour, the presence of a carboxylic acid in the proline ring seems to play a crucial role in the rearrangement, probably due to an intramolecular hydrogen bond. To confirm this hypothesis, deuterium exchanges in mass spectrometric experiments and a conformational analysis via computational methods were performed. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of 17β‐estradiol in bovine plasma: development of a highly sensitive technique by ion trap gas chromatography–tandem mass spectrometry using negative chemical ionization
Authors: Biancotto Giancarlo , Angeletti Roberto , Traldi Pietro , Silvestri Massimiliano , Saccon Mauro , Guidugli Federico 
Published: December 2002

AbstractA novel approach to the determination of 17β‐estradiol in bovine plasma is presented. The observed enhanced sensitivity is gained by the application of tandem mass spectrometry (MS) fragmentation to a stable, well characterized negative ion produced by chemical ionization (methane as reagent gas). A specific derivatizing reactant is employed (pentafluorobenzyl bromide), combined with bis‐trimethylsilyltrifluoroacetamide, to favor the formation of a diagnostic precursor negative ion. Plasma samples are purified through a C18 solid phase extraction column and derivatized before gas chromatography–MS analysis. The accuracy and the precision of the method, tested over a set of spiked samples, were satisfactory. The limit of detection was found to be 5 pg ml−1 and the limit of quantification was fixed at 20 pg ml−1. The fragmentation pattern is fully explained and the method is applicable for the official analysis of bovine plasma for the detection of 17β‐estradiol according to the European criteria 256/93 and to the draft SANCO/1805/2000 rev. 3. The quantification of incurred positive samples was performed according to the proposed procedure and compared with the results obtained by standardized radio immuno assay; the estimated concentrations were significantly similar. Copyright © 2002 John Wiley & Sons, Ltd.
Direct stereochemical assignment of hexose and pentose residues in flavonoid O‐glycosides by fast atom bombardment and electrospray ionization mass spectrometry
Authors: Cuyckens Filip , Shahat Abdelaaty A. , Pieters Luc , Claeys Magda 
Published: December 2002

AbstractMass spectrometric methods have been developed which allow the direct stereochemical assignment of terminal monosaccharide residues in flavonoid O‐glycosides without the need for chemical hydrolysis. Standards containing a glucose, galactose, mannose, xylose, arabinose or apiose residue were examined because these monosaccharides are by far the most commonly encountered in flavonoid glycosides. Following acetylation, the major peracetylated sugar related fragments, generated by fast atom bombardment (FAB) or electrospray ionization (ESI), were selected for collisional activation employing a broad range of collision energies. Both FAB and ESI proved to be useful as ionization techniques. Stereoselective fragmentation was achieved and allowed us clearly to differentiate and characterize isomeric monosaccharide residues. The method developed was successfully applied to an unknown flavonoid containing a terminal pentose and hexose residue which was isolated from Farsetia aegyptia. Copyright © 2002 John Wiley & Sons, Ltd.
Isomerization and dissociation of C2X5+ and C2X4+· ions (X = Cl, F) from chlorofluoroethanes in an ion trap mass spectrometer
Authors: Marotta Ester , Paradisi Cristina 
Published: December 2002

AbstractThe collision‐induced dissociation of C2X5+ (C2Cl2F3+, C2Cl3F2+ and C2Cl4F+) and C2X4+· ions (C2ClF3+·, C2Cl2F2+·, and C2ClF3+·) derived from three chlorofluoroethanes (the isomeric 1,1,1‐ and 1,1,2‐trichlorotrifluoroethane and 1,1,1,2‐tetrachlorodifluoroethane) was investigated by means of multi‐stage mass spectrometric (MSn) experiments in an ion trap mass spectrometer. The observation of a common dissociation pattern for ions of any given elemental composition suggests that the experiments could not differentiate isomeric C2X5+ ions formed from different neutral precursors and originally having different structures. For any given elemental composition, a common dissociation pattern was observed, suggesting that energy barriers for isomer interconversion are lower than for dissociation. For ions containing two or more fluorine atoms, the major (in some cases unique) dissociation involves C—C cleavage to form CX3+ and CF2. Energetically, CF2 loss is always the most favorable reaction; mechanistically it implies, at least in some cases, rearrangement via halogen transfer from one carbon to the other (for example, in the case of the C2Cl2F3+ species derived from 1,1,1‐trichlorotrifluoroethane, which should have initially the Cl2C+—CF3 structure). Similar behavior was observed with C2X4+· ions produced both from the three chlorofluoroethanes and from model alkenes (trifluorochloroethene and tetrachloroethene). The dissociation behavior of these C2X4+· species is characteristic of the ion composition, with no memory of the original neutral precursor structure. Specifically, C2Cl2F2+· ions dissociate uniquely via loss of CF2, C2ClF3+· ions eliminate preferentially CF, with CF2 loss being only a minor reaction, whereas C2Cl3F+· and C2Cl4+· dissociate exclusively via Cl elimination. Copyright © 2002 John Wiley & Sons, Ltd.
Gene expression profiling using advanced mass spectrometric approaches
Authors: Paša‐Tolić Ljiljana , Lipton Mary S. , Masselon Christophe D. , Anderson Gordon A. , Shen Yufeng , Tolić Nikola , Smith Richard D. 
Published: December 2002

AbstractIn the era of systems biology, computational and high‐throughput experimental biological approaches are increasingly being combined to provide global snapshots of entire genomes and proteomes under tissue‐ and disease‐specific conditions. The aim is to identify proteins changing in concentration and/or post‐translational state and/or location, and develop a better molecular level understanding of the operation of biological systems. Here we describe an approach for comparative proteomics that builds upon the combination of high‐performance nano‐scale separations with the high‐mass measurement accuracy, mass‐resolving power and sensitivity of Fourier transform ion cyclotron resonance mass spectrometry to provide broad dynamic range, comprehensive and quantitative proteome measurements. Copyright © 2002 John Wiley & Sons, Ltd.
Nitrification activity in tropical rain forest soils of the Coastal Lowlands and Atherton Tablelands, Queensland, Australia
Authors: Kiese Ralf , Papen Hans , Zumbusch Elisabeth , Butterbach‐Bahl Klaus 
Published: December 2002

AbstractIntact soil cores from a montane tropical rain forest site in the Atherton Tablelands (Kauri Creek) and from a lowland tropical rain forest site in the Coastal Lowlands (Bellenden Ker), Queensland, Australia were investigated during different hygric seasons for the magnitude of gross nitrification rates using the Barometric Process Separation technique (BaPS). Pronounced seasonal variations of gross nitrification rates were found at both sites with highest values during the transition period between dry and wet season (montane site: 24.0 mg N (kg SDW)—1 d—1; lowland site: 13.1 mg N (kg SDW)—1 d—1) and significantly lower rates of gross nitrification during the dry and wet season. Rates of gross nitrification were always higher at the montane site than at the lowland site, but the opposite was found for N2O emissions. The results indicated that the high losses of N2O at the lowland tropical rain forest site may be contributed largely by high denitrification activity due to its wetter and warmer climate as compared to the dryer and colder climate at the montane tropical rain forest site. This conclusion was supported by analysis of cell numbers of microbes involved in N‐cycling. Higher numbers of denitrifiers were present at the lowland site, whereas higher numbers of nitrifiers were found at the montane site.
Polycyclic aromatic hydrocarbons (PAHs) in peat and plants from selected peat‐bogs in the north‐east of Poland
Authors: Malawska Małgorzata , Bojakowska Izabela , Wiłkomirski Bogusław 
Published: December 2002

AbstractThe concentrations of polycyclic aromatic hydrocarbons (PAHs) were analyzed in samples of peat and of two plant species (Pinus sylvestris and Ledum palustre) overgrowing peat‐bogs in the north‐east of Poland. Peat samples were collected from different depths according to the stratigraphic profile of the peat bogs. The total concentrations of the 16 anthropogenic PAHs (15 from the US EPA list and benzo[e]pyrene) in all peat samples were between 70 and 439 ng g—1. The concentration for the same compounds in pine needles (Pinus sylvestris) and Dutch Myrthe leaves (Ledum palustre) varied between 194 and 1039 ng g—1. A noticeably high fluorene concentration in Dutch Myrthe leaves was found at some sites. In all peat samples 3‐ring compounds were predominant (55 to 319 ng g—1). There were less 4‐ring PAHs (15 to 110 ng g—1) and the least common PAHs were 5‐ring and 6‐ring compounds (0 to 81 ng g—1 for both groups). In some peat samples, the perylene concentration largely exceeds of the total concentration of all the other PAHs investigated. The high content of perylene in bottom layers could result from the processes of perylene sorption from water during peat‐bog formation or from biogenic formation of perylene.
Some investigations into the behavior of pentabromodiphenyl ether (PeBDE) in soils
Authors: Litz Norbert 
Published: December 2002

AbstractPentabromodiphenyl ethers (PeBDEs) are components of brominated flame retardants which have been detected in various environmental media (waste water, sewage sludge, sediments, and aquatic biota). They are ”︁priority pollutants”. Sewage sludge from 20 different sewage treatment plants under summer and winter conditions showed PeBDE levels in primary sludge of up to 70 μg kg—1 with a dominant range of 5—20 μg kg—1. To insure a safe sludge use in agriculture, sorption, mobility, and dissipation experiments using soil substrates were conducted. PeBDE was bound strongly to organic matter (Koc = 125,000) while Kd values after FREUNDLICH of about 90 and 700 were obtained for clay and sand, respectively, and of 45,000 for humus. Less than 0.001 % was found in eluates from laboratory lysimeters, and about 91 % remained at a depth of 0—3 cm. Thus PeBDE has a low mobility. In the indicative dissipation tests, the recovery rate after 3 weeks was about 50 %, and about 20—25 % was still detectable after 8 weeks. PeBDE proved to be less persistent than previously assumed. A formation of bound residues is presumed to be likely. Only a small difference was found between aerobic and anaerobic dissipation. The strong fixation in soil suggests a need to clarify whether PeBDE accumulates in soil.
Distribution of Cd in the vicinity of a metal smelter: Interpolation of soil Cd concentrations with regard to regulative limits
Authors: Altfelder Sven , Beyer Christof , Duijnisveld Wilhelmus H. M. , Schneider Jürgen , Streck Thilo 
Published: December 2002

AbstractThe German soil protection regulation (BBodSchV) requires the investigation and evaluation of sites with known, or suspected contamination. The purpose of this study is the application of geostatistical methods to locate hazardous zones within such a site and to estimate the amount and uncertainty of the contaminant load in these zones. The study site is an area around a metal smelter in the city of Nordenham, Germany, where among other heavy metals, Cd was released to the environment by dust emissions for many decades. In an earlier study soil cores were taken in the area and analyzed for Cd using various extraction methods. After translation of data to results corresponding to a single extraction method using linear regression analysis, Cd concentrations were mapped by ordinary and lognormal kriging. Crossvalidation showed that both methods perform similarly. However, neither ordinary nor lognormal kriging were able to account for the uncertainty of the kriged estimates. We repeated ordinary kriging with a relative variogram having a unit sill. The estimated relative kriging variance was scaled locally. This method considerably improved the estimation of uncertainty. Subsequently, we estimated Cd contents for the land use dependent size of support as specified in the BBodSchV. The kriged Cd estimates as well as their uncertainty were evaluated with regard to limits set by the BBodSchV. Parts of the area which may be declared safe based on merely the kriged estimates, can actually exceed a sanction or test limit by a chance of up to 50 % when uncertainty is also considered. Within the BBodSchV a recommended limit should therefore always be accompanied by a tolerable uncertainty that it may be exceeded on a given support (e.g. 5 %).