bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissipation of the herbicide dithiopyr in soil and residues in wheat (Triticum aestivum L) grain under Indian tropical conditions
Authors: Saikia Nirmali , Kulshrestha Gita 
Published: December 2002

AbstractDissipation of dithiopyr in soil was monitored after application to wheat crop as pre‐ or post‐ emergence applications at two rates, viz 100 and 200 g AI ha−1. The level of dithiopyr in the soil was assessed by gas chromatography, and its disappearence was found to follow a first‐order decay curve irrespective of rate or method of application. The half‐life in soil ranged between 17.3 and 25.0 days and residues at harvest (150 days after application) ranged between 4.0 and 8.8% of amounts applied. Investigation of microbial degradation of dithiopyr was conducted in minimal salt and Czapek Dox media in which 80% of the compound degraded within 15 days. Residues were not detected in wheat grain at harvest.© 2002 Society of Chemical Industry
Derivatization procedures for the detection of estrogenic chemicals by gas chromatography/mass spectrometry
Authors: Ding Wang‐Hsien , Chiang Cheng‐Che 
Published: December 2002

AbstractThis work evaluated derivatization procedures for detecting both natural and synthetic estrogenic chemicals by gas chromatography/mass spectrometry (GC/MS). Different silylating agents, mainly trimethylsilylating (TMS) agents, were compared, and the roles of various content of trimethylchlorosilane (TMCS, as a stimulator) were investigated. The difference in the abundances of the derivatives was caused by the steric hindrance of multiple hydroxyl groups and ethynyl groups in the structures of estrogenic chemicals. The use of TMCS produces an increase in the derivatization yield, especially for the compounds with multiple hydroxyl groups (i.e., 17β‐estradiol (E2) and estriol (E3)). Mass spectra of O‐TMS derivatives and tentative fragmentation profiles are proposed. Molecular ions were the base peaks for all the derivatives, and were used as the quantitation ions to obtain maximum detection sensitivity and specificity. Sample enrichment was achieved by Oasis® HLB solid‐phase extraction cartridges. The quantitation limits of these compounds ranged from 5 to 10 ng/L in 1000‐mL water samples. Recovery of the estrogenic chemicals in spiked various water samples ranged from 78 to 102% while relative standard deviation (RSD) ranged from 1 to 15%. Copyright © 2002 John Wiley & Sons, Ltd.
Evaluation of protocols for reproducible electrospray in‐source collisionally induced dissociation on various liquid chromatography/mass spectrometry instruments and the development of spectral libraries
Authors: Bristow Anthony W. T. , Nichols William F. , Webb Kenneth S. , Conway Brian 
Published: December 2002

AbstractMass spectral libraries provide a tool for identifying unknown compounds using both molecular weight and fragmentation information. Mass spectrometers with electrospray ionisation (ESI) and atmospheric chemical ionisation (ApCI) sources have the capability to produce data of this type using in‐source collisionally induced dissociation (CID), and in‐source CID libraries can be created. Due to the variation in electrospray source design from different instrument manufacturers, the production of reproducible in‐source CID spectra that can be used in libraries for all instrument types is not a trivial task. To date, the evaluation of the production of in‐source CID libraries has tended to focus on similar instruments from one manufacturer. The studies have also tended to focus on specific compound classes, with a limited molecular weight range.This report describes the findings from the investigation of protocols for the creation of mass spectral libraries using ESI in‐source CID on six instruments from four different manufacturers. The overall goal was to create a spectral library for the identification of unknowns. The library could then be applied across all manufacturers' electrospray instruments.Two different experimental protocols were attempted. The first used a tuning compound to establish standard ESI source conditions, with fixed fragmentation potentials. The second involved the attenuation of the [M + H]+ ion to a known degree. A diverse range of compounds (pharmaceutical, photographic, pesticides) was tested to establish the reproducibility of the spectra on the six instruments. Both protocols produced spectra on the various instruments that in many cases were very similar. In other examples, the spectra differed not only in their relative ion abundances, but also in terms of the spectral content. Important observations regarding the effect of ion source design are also reported.The degree of spectral reproducibility was calculated off‐line by comparing the five most abundant ions (20% for each ion that matches) from each spectrum on each instrument. This approach was adopted, as we do not possess a software package that met our requirements for spectral comparison. Match factors (% fit) were calculated by comparing each spectrum against the spectra recorded for the same compound and then for all other compounds, on each instrument. The % fit values derived by the off‐line approach gave a clear view of the spectral reproducibility from instrument to instrument and also discriminated the spectra of the various compounds from each other. The applicability of this approach was tested using a blind trial in which several compounds were presented as unknowns, their in‐source CID spectra recorded and the five‐ion approach used for identification. Copyright © 2002 John Wiley & Sons, Ltd.
Different electrospray tandem mass spectrometric approaches for rapid characterization of phospholipid classes of Curosurf®, a natural pulmonary surfactant
Authors: Pelizzi Nicola , Catinella Silvia , Barboso Silvia , Zanol Margherita 
Published: December 2002

AbstractCurosurf® is a pulmonary surfactant used in the treatment or prophylaxis of neonatal respiratory distress syndrome. It contains low molecular weight hydrophobic apoproteins and a series of lipids including phosphatidylcholines, lisophosphatidylcholines, phosphatidylethanolamines, sphingomyelins, phosphatidylinositols, phosphatidylglycerols and phosphatidylserines. In the present work, a rapid method to qualitatively map the Curosurf® phospholipid classes without prior derivatization or chromatographic separations is described. In particular, a series of specific electrospray tandem mass spectrometric (ES‐MS/MS) experiments, i.e. product ion, precursor ion and neutral loss scans, were chosen on the basis of the chemical nature of each phospholipid class and then used to identify single components of the commercial suspension, directly infused into the ion source of the mass spectrometer. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of non‐steroidal estrogens in breast milk, plasma, urine and hair by gas chromatography/mass spectrometry
Authors: Choi Man Ho , Kim Kyoung‐Rae , Hong Jong Ki , Park Song Ja , Chung Bong Chul 
Published: December 2002

AbstractIt is suspected that all the natural estrogens occurring in the human body, as well as dietary and synthetic estrogens, diversely affect the endocrine system depending on their exposure patterns. More rapid, reliable and accurate measurements of these compounds in various biological matrices are thus becoming an important task. After solid‐phase extraction using an Oasis HLB extraction cartridge, the estrogen concentrates were derivatized with a mixture of N‐methyl‐N‐trifluorotrimethylsilylacetamide/ammonium iodide/dithioerythritol (1000:4:5, v/w/w) for analysis by gas chromatography/mass spectrometry in the selected ion‐monitoring (SIM) mode. The qualitative identification of estrogens detected in SIM mode was further confirmed by tandem mass spectrometry using low‐energy collision‐induced dissociation (CID) mode. The method for the assay of the 20 estrogens was linear over the ranges of 1–1000 µg/L for biological fluids and 1–200 µg/kg for hair with high correlation coefficient (>0.99). The limits of quantitation (LOQ) ranged from 1.0–10 µg/L (or µg/kg) and the limit of detection ranged from 0.2–3 µg/L (or µg/kg). The average precision (% CV) and accuracy (% bias) of the method determined at the LOQ, low, and medium concentrations were in the ranges 2.6–9.2 and −4.1–7.7, respectively. The average extraction recovery of the estrogens from plasma and hair at the three concentration levels varied in the ranges 77–103% (1.9–14.3% CV) and 73–104% (3.1–14%), respectively. The distribution patterns of the estrogens were characteristic of each biosample. Five estrogens in the range 1.5–44.9 µg/L were measured in breast milk, 8 estrogens in the range 3.5–322 µg/L in plasma, 12 estrogens at 1.2–442 µg/L in urine, and biochanin‐A at 13.2–39.1 µg/kg in hair. Because of its high sensitivity, good precision and specificity, the present method was found suitable for the trace analysis of dietary and synthetic estrogens in complex biosamples such as breast milk, plasma, urine and hair. Copyright © 2002 John Wiley & Sons, Ltd.
Electron capture dissociation of weakly bound polypeptide polycationic complexes
Authors: Haselmann Kim F. , Jørgensen Thomas J. D. , Budnik Bogdan A. , Jensen Frank , Zubarev Roman A. 
Published: December 2002

AbstractWe have previously reported that, in electron capture dissociation (ECD), rupture of strong intramolecular bonds in weakly bound supramolecular aggregates can proceed without dissociation of weak intermolecular bonds. This is now illustrated on a series of non‐specific peptide‐peptide dimers as well as specific complexes of modified glycopeptide antibiotics with their target peptide. The weak nature of bonding is substantiated by blackbody infrared dissociation, low‐energy collisional excitation and force‐field simulations. The results are consistent with a non‐ergodic ECD cleavage mechanism. Copyright © 2002 John Wiley & Sons, Ltd.
Electrospray ionization mass spectra of monoimidazole/polyamine conjugates
Authors: Zhu Changjin , Jiang Yanfeng , Yang Xiaoli , Zhao Yufen 
Published: December 2002

AbstractImidazole/polyamine amides are biologically important molecules due to their specific DNA binding activity, and much attention has been attracted to the synthesis of their derivatives or analogues. In the present studies, the fragmentation of a series of synthetic monoimidazole/polyamine amides was investigated using electrospray ionization mass spectrometry (ESI‐MS) combined with tandem mass spectrometry (ESI‐MS/MS). All of the monoimidazole/polyamine amides produced the fragment ion m/z 183 except for the monoimidazole/ethyldiamine amide. The diamine amides produced this ion after the elimination of an alkene, the triamine amides produced it via their corresponding diamine amide fragments, and the tetraamine amide via its triamine and then diamine amide fragments. The characterization of the mass spectra for the different polyamine amides allowed identification of a specific product from the N‐acylation of spermidine, and should assist further study of the polyamine amides in DNA binding action. Copyright © 2002 John Wiley & Sons, Ltd.
Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry of lipids: ionization and prompt fragmentation patterns
Authors: Al‐Saad Khalid A. , Zabrouskov Vladimir , Siems William F. , Knowles N. Richard , Hannan Richard M. , Hill Herbert H. 
Published: December 2002

AbstractIonization and prompt fragmentation patterns of triacylglycerols, phospholipids (PLs) and galactolipids were investigated using matrix‐assisted laser desorption/ionization (MALDI). Positive ions of non‐nitrogen‐containing lipids appeared only in the sodiated form, while nitrogen‐containing lipids were detected as both sodiated and protonated adducts. Lipids containing acidic hydroxyls were detected as multiple sodium adducts or deprotonated ions in the positive and negative modes, respectively, with the exception of phosphatidylcholines. The positive MALDI spectra of triacylglycerols contained prompt fragments equivalent to the loss of RCOO− from the neutral molecules. Prompt fragment ions [PL–polar head]+ were observed in the positive MALDI spectra of all phospholipids except phosphatidylcholines. The phosphatidylcholines produced only a minor positive fragment corresponding to the head group itself (m/z 184). Galactolipids did not undergo prompt fragmentation. Post‐source decay (PSD) was used to examine the source of prompt fragments. PSD fragment patterns indicated that the lipid prompt fragment ions did not originate from the observed molecular ions (sodiated or protonated), and suggested that the prompt fragmentation followed the formation of highly unstable, probably protonated, precursor ions. Pathways leading to the formation of prompt fragment ions are proposed. Copyright © 2002 John Wiley & Sons, Ltd.
Mammalian reovirus core protein µ2 initiates at the first start codon and is acetylated
Authors: Swanson Magdalena I. , She Yi‐Min , Ens Werner , Brown Earl G. , Coombs Kevin M. 
Published: December 2002

AbstractMammalian reovirus is an enteric virus that contains a double‐stranded RNA genome. The genome consists of ten RNA segments that encode eight structural and three non‐structural proteins. The structural proteins form a double‐layered structure. The innermost layer, called the core, consists of five proteins (λ1, λ2, λ3, µ2, and σ2). Protein λ3 is the RNA‐dependent RNA polymerase (RdRp) and µ2 is thought to be an RdRp cofactor. Translation of most reovirus proteins is known to commence at the first start codon. However, the translation initiation site of the viral core protein µ2, encoded by the M1 RNA segment, has been in dispute. Although the theoretical molecular weight of µ2 is 83 267 Da the actual molecular weight is unknown because µ2 runs aberrantly in SDS‐PAGE and has resisted characterization by Edman degradation, indicating that the amino terminus is post‐translationally modified. In this study, we used proteolysis coupled with MALDI‐Qq‐TOFMS to determine that translation of µ2 initiates at the first AUG codon, that its actual molecular weight approximates the theoretical value of 83 kDa, that the amino terminal methionine residue is removed, and that the next amino acid (alanine) is post‐translationally acetylated. Copyright © 2002 John Wiley & Sons, Ltd.
Solid‐phase microextraction liquid chromatography/tandem mass spectrometry for the analysis of chlorophenols in environmental samples
Authors: Sarrión M. N. , Santos F. J. , Moyano E. , Galceran M. T. 
Published: December 2002

AbstractLiquid chromatography with atmospheric pressure chemical ionisation mass spectrometry (LC/APCI‐MS), using negative ion detection in a triple quadrupole instrument, was used for the determination of chlorophenols (CPs) in environmental samples. In‐source collision‐induced dissociation (CID) was compared with MS/MS fragmentation. In general, less fragmentation was observed in MS/MS as compared with in‐source CID, with the latter providing more intense fragment ions due to chemical ionisation. Under MS/MS conditions [M − H − HCl]− was the main fragment ion observed for all compounds except for pentachlorophenol, which showed no fragmentation. For multiple reaction monitoring (MRM) acquisition mode, the transition from [M − H]− to [M − H − HCl]− was selected, leading to detection limits down to 0.3 ng injected. Direct and headspace‐solid‐phase microextraction (HS‐SPME) were used as preconcentration procedures for the analysis of CPs in wood and in industrially contaminated soils. CPs were quantified by standard addition, which led to good reproducibility (RSD between 4 and 11%) in both SIM and MRM modes, and detection limits down to ng/g. The combination of MS/MS and in‐source CID allowed confirmation of the presence of CPs in environmental samples. Copyright © 2002 John Wiley & Sons, Ltd.
Structural characterization of chromone C‐glucosides in a toxic herbal remedy
Authors: Wang Wu , Cuyckens Filip , Van den Heuvel Hilde , Apers Sandra , Pieters Luc , Steenkamp Vanessa , Stewart Michael J. , Luyckx Valerie A. , Claeys Magda 
Published: December 2002

AbstractTwo novel compounds, 8‐C‐D‐glucopyranosyl‐7‐hydroxy‐5‐methylchromone‐2‐carboxylic acid and a 2‐O′‐p‐coumaroyl derivative thereof, were identified in a herbal tea that caused severe vomiting in a South African patient who had taken the traditional remedy to clean his stomach. For structural characterization, electrospray (ES) ionization in combination with collision‐induced dissociation (CID) and tandem mass spectrometry (MS/MS) were used, as well as UV and nuclear magnetic resonance (NMR) spectroscopy. Specific ions or neutral losses generated under conditions of ES‐MS/CID/MS permitted the establishment of structural features such as the free carboxyl group, the C‐hexosidic part and the p‐coumaroyl group. NMR spectroscopy was necessary to support the structure of the chromone‐type aglycone and the glucosidic parts. Since the compounds are structurally related to aloesin and aloeresin A, which are chemotaxonomic markers of Aloe species, and have not been previously reported, we propose that they were formed by oxidative degradation during preparation of the herbal tea from an Aloe species or during its storage. Copyright © 2002 John Wiley & Sons, Ltd.
Investigation of matrix effects in bioanalytical high‐performance liquid chromatography/tandem mass spectrometric assays: application to drug discovery
Authors: Mei Hong , Hsieh Yunsheng , Nardo Cymbylene , Xu Xiaoying , Wang Shiyong , Ng Kwokei , Korfmacher Walter A. 
Published: December 2002

AbstractA series of studies was performed to investigate some of the causes for matrix effects (‘ion suppression’ or ‘ion enhancement’) in bioanalytical high‐performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) assays. Previous studies have reported that matrix effects are mainly due to endogenous components in biological fluids and are a greater concern for electrospray ionization (ESI) than for atmospheric pressure chemical ionization (APCI). In this report we demonstrate that: (1) matrix effects can also be caused by exogenous materials, such as polymers contained in different brands of plastic tubes, or Li‐heparin, a commonly used anticoagulant; (2) matrix effects are not only ionization mode (APCI or ESI) dependent, but also source design (Sciex, Finnigan, Micromass) dependent; and (3) for at least one vendor's design, we found the APCI mode to be more sensitive to matrix effects than the ESI mode. Based on these findings, we have proposed the following simple strategies to avoid matrix effects: (1) select the same brand of plastic tubes for processing and storing plasma samples and spiked plasma standards; (2) avoid using Li‐heparin as the anticoagulant; and (3) try switching the ionization mode or switching to different mass spectrometers when matrix effects are encountered. These three strategies have allowed us to use protein precipitation and generic fast LC techniques to generate reliable LC/MS/MS data for the support of pharmacokinetic studies at the early drug discovery stage. Copyright © 2002 John Wiley & Sons, Ltd.
The unanticipated loss of SO2 from sulfonamides in collision‐induced dissociation
Authors: Wang Zhen , Hop Cornelis E. C. A. , Kim Mi‐Sook , Huskey Su‐E. W. , Baillie Thomas A. , Guan Ziqiang 
Published: December 2002

AbstractA potent and selective sulfonamide β3 agonist with an excellent pharmacokinetic profile has recently been synthesized. During the analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS) of metabolites of the sulfonamide N‐{4‐[2‐(2‐hydroxy‐2‐pyridin‐3‐ylethylamino)ethyl]phenyl}‐4‐[4‐(4‐trifluoromethylphenyl)thiazol‐2‐yl]benzulfonamide (compound A), we observed loss of 64 Da for a few of the metabolites in the negative ion mode. Accurate mass measurements performed with Fourier transform ion cyclotron resonance (FTICR) mass spectrometry and quadrupole time‐of‐flight (Q‐TOF) mass spectrometry suggested that the loss of 64 Da corresponded to the loss of SO2. The same phenomenon was observed for a group of structurally related and commercially available compounds that also contain a sulfonamide moiety. MS/MS analysis of the fragment ions that had lost SO2 in the ion source suggested that these ions were covalently bound rather than ion‐molecule complexes. The neutral loss involving the cleavage of two bonds was unanticipated and suggested a complex rearrangement process. A mechanism for the loss of SO2 has been proposed. Copyright © 2002 John Wiley & Sons, Ltd.
An Adaptive Controller for Two Cooperating Flexible Manipulators
Authors: Damaren Christopher J. 
Published: December 2002

AbstractThe control problem for two serial flexible multilink robots which carry
a common rigid payload is considered. An adaptive controller with feedback
and feedforward elements is presented which can track a prescribed trajectory
for the payload with simultaneous vibration suppression when the manipulated
payload is sufficiently large. A free load‐sharing parameter appears in the
passivity‐based control law which allows the torque requirement to be shared
between the two arms in a largely arbitrary fashion. Simulation results using
a complex model are given which demonstrate excellent tracking performance
in the face of complete payload uncertainty. © 2003 Wiley Periodicals,
Inc.
Progression of the stacked Golgi compartments in the yeast Saccharomyces cerevisiae by overproduction of GDP–mannose transporter
Authors: Hashimoto Hitoshi , Abe Masato , Hirata Aiko , Noda Yoichi , Adachi Hiroyuki , Yoda Koji 
Published: December 2002

AbstractThe Golgi compartments of the yeast Saccharomyces cerevisiaeare dispersed within the cytoplasm, in contrast to the stacked cisternae in the mammalian cell, and consequently are observed as a punctate pattern by immunofluorescent staining of Golgi‐marker proteins. The VIG4/VRG4 gene encodes the essential yeast GDP–mannose transporter, which is a polytopic membrane protein in the early and medial Golgi compartments. Upon overexpression of this gene by the aid of a strong promoter and multicopy vector, we found that stacked multivesicular structures, which resembled the cisternae of mammalian Golgi apparatus, had developed in S. cerevisiae. Immuno‐electron microscopy showed that the GDP–mannose transporter was located on the stacked cisternae. Immuno‐isolation and immunoblotting analyses of the vesicles showed that the overproduced GDP–mannose transporter also co‐localized with the Golgi glycosyltransferases, but not with the ER‐ or late Golgi‐marker proteins as in the control cell. We propose that the localization mechanism of the GDP–mannose transporter in the Golgi compartment would be efficient and hardly saturable, and therefore the overproduced protein induced a progression of Golgi‐like compartments rather than being mislocalized in other compartments, such as the ER or a vacuole. Copyright © 2002 John Wiley & Sons, Ltd.