bluuebunny/crossref_metadata_2025 huggingface dataset:
Stabilization of a cocontinuous phase morphology by a tapered diblock or triblock copolymer in polystyrene‐rich low‐density polyethylene/polystyrene blends
Authors: Harrats C. , Fayt R. , Jérôme R. , Blacher S.
Published: December 2002

The stability against the thermal annealing of a cocontinuous two‐phase morphology developed in polystyrene (PS)/low‐density polyethylene (LDPE) blends containing 80 wt % PS was investigated. Blends containing 1, 5, and 10 wt % of a tapered diblock poly(styrene‐block‐hydrogenated butadiene) (P(S‐b‐hB)) or triblock poly(styrene‐block‐hydrogenated butadiene‐block‐styrene) (P(S‐hB‐S)) copolymer were melt‐blended with roll‐mill mixing equipment. The efficiency of each of the two copolymers in stabilizing against coalescence the cocontinuous morphology was examined. The tensile properties of the resulting blends, annealed and nonannealed, were also examined in relation to the morphology induced by thermal annealing. The phase morphology was studied by optical and scanning electron microscopy. With computer‐aided image analysis, it was possible to obtain a measurable characteristic parameter to quantify the cocontinuous phase morphology. When it was necessary, the extraction of one phase with a selective solvent was performed. Although the observed differences were subtle, the tapered diblock exhibited a more efficient compatibilizing activity than the triblock copolymer, particularly at a low concentration of about 2 wt %. The superiority of the tapered diblock over the triblock might be due to its ability to quantitatively locate at the LDPE/PS interface and consequently form a more efficient barrier against the subsequent breakup of the elongated structures of the cocontinuous phase morphology. The tensile properties of the triblock‐modified blends were more sensitive to thermal annealing than the tapered‐modified ones. This deficiency was ascribed to the phase morphology coarsening of the dispersed polyethylene phase. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 202–216, 2003
Parameterisation, evaluation and comparison of pesticide leaching models to data from a Bologna field site, Italy
Authors: Garratt James A , Capri Ettore , Trevisan Marco , Errera Giuseppe , Wilkins Richard M
Published: December 2002

Effective prediction of pesticide fate using mathematical models requires good process descriptions in the models and good choice of parameter values by the user. This paper examines the ability of seven pesticide leaching models (LEACHP, MACRO, PELMO, PESTLA, PLM, PRZM and VARLEACH) to describe an arable field environment where sunflowers are grown in the Po Valley, northern Italy. Two pesticides were considered, aclonifen and ethoprophos. The models were evaluated in terms of their ability to reproduce field data of soil water content and pesticide residues in the soil and ground water. The evaluation was based on a combination of calibrated and uncalibrated runs. The results from the models were compared with each other to explore the differences between the models. The models varied in their ability to predict soil water content in the summer: the capacity models PRZM, PELMO and VARLEACH predicted less drying than MACRO, PESTLA, PLM and LEACHP. The models varied in their ability to simulate the persistence of the pesticides in the soil. Differences in the simulated pesticide degradation rate were observed between the models, due to variations in the simulated soil water content and soil temperature, and also differences in the equation linking degradation rate to soil water content. There were large differences among the predictions of the models for the mean leaching depth of ethoprophos. PRZM, PELMO, PESTLA and LEACHP all showed similar mean leaching depth to each other, whereas VARLEACH predicted lower ethoprophos mobility and PLM and MACRO predicted greater mobility. All the models overpredicted dispersion of ethoprophos through the soil profile, as compared to the field data. None of the models was able to simulate the field data of rapid leaching of pesticide to ground water except PLM after calibration of the percentage of macropores in the mobile pore space. More work is required in the parameterisation of macropore flow for those models that include this process.

© 2002 Society of Chemical Industry
Comparative effects of vetiver oil, nootkatone and disodium octaborate tetrahydrate on Coptotermes formosanus and its symbiotic fauna
Authors: Maistrello Lara , Henderson Gregg , Laine Roger A
Published: December 2002

The potential of vetiver oil and nootkatone as wood treatments against Coptotermes formosanus Shiraki was examined by assessing the effects on termite tunneling, feeding activity and survival, and the consequences on the symbiont protozoa responsible for wood digestion. Comparisons were made with non‐treated wood (control), wood treated with the borate compound Tim‐Bor® (a commonly used lumber preservative) and absence of a food source (starved termites), using choice and no‐choice tests. All wood slices were prepared at the same time using a 10 g liter−1 solution of each substance and were tested in four different sessions over one year to investigate longevity of the effects. Termites had to tunnel through sand to exploit the food sources, consisting of two wood slices, placed on opposite sides of the experimental enclosure. No‐choice tests showed that in the presence of vetiver oil or nootkatone, tunneling activity was always the lowest; wood consumption, termite survival and flagellate numbers and species distribution were significantly different from the control and similar to the results obtained for starved termites and with Tim‐Bor–treated wood. Nootkatone negatively affected termites for 12 months and was longer lasting than vetiver oil. In choice tests, when vetiver oil or nootkatone were present, termites exhibited a significant preference for non‐treated wood. Our results confirmed both the toxicity and absence of repellency of Tim‐Bor®. Vetiver oil and especially nootkatone affected Formosan subterranean termites and their protozoa, acting as arrestants, repellents and feeding deterrents, and represent a promising natural alternative for the control of this invasive pest.

© 2002 Society of Chemical Industry
Synthesis and insecticidal activity of benzoheterocyclic analogues of N′‐benzoyl‐N‐(tert‐butyl)benzohydrazide: Part 2. Introduction of substituents on the benzene rings of the benzoheterocycle moiety
Authors: Sawada Yoshihiro , Yanai Toshiaki , Nakagawa Harumi , Tsukamoto Yoshihisa , Yokoi Shinji , Yanagi Mikio , Toya Tetsuya , Sugizaki Hiroyasu , Kato Yasuhito , Shirakura Hidetoshi , Watanabe Tetsuo , Yajima Yoshimi , Kodama Seiichirou , Masui Akio
Published: December 2002

A series of N′‐benzoheterocyclecarbonyl‐N‐tert‐butyl‐3,5‐dimethylbenzohydrazide analogues possessing a variety of substituents on the benzene rings of the benzoheterocyle moieties were synthesized and tested for their insecticidal activity. The introduction of a methyl group at the R1 position of the benzoheterocycle moiety strongly increased the insecticidal activity. Among the analogues synthesized, N′‐tert‐butyl‐N′‐(3,5‐dimethylbenzoyl)‐5‐methyl‐6‐chromanecarbohydrazide showed the highest insecticidal activity (LC50 = 0.89 mg litre−1).

© 2002 Society of Chemical Industry
Acaricidal activity of Cnidium officinale rhizome‐derived butylidenephthalide against Tyrophagus putrescentiae (Acari: Acaridae)
Authors: Kwon Ji‐Hoon , Ahn Young‐Joon
Published: December 2002

The acaricidal activity of materials derived from the rhizome of Cnidium officinale Makino against Tyrophagus putrescentiae Schrank adults was examined using direct contact application and fumigation methods, and compared with that of benzyl benzoate and N,N‐diethyl‐m‐toluamide (DEET). The biologically active constituent of the Cnidium rhizome was identified as butylidenephthalide by spectroscopic analyses. On the basis of 24‐h LD50 values, acaricidal activity was more pronounced with butylidenephthalide (5.80 µg cm−2) than with benzyl benzoate (9.75 µg cm−2) and DEET (16.26 µg cm−2). In typical poisoning symptoms, butylidenephthalide resulted in lethargy of treated mites, leading to death without knockdown, whereas benzyl benzoate and DEET caused death associated with uncoordinated behaviour. In a fumigation test with T putrescentiae adults, butylidenephthalide was much more effective in closed containers than in open ones, indicating that the effects of this compound were largely due to action in the vapour phase. Naturally occurring C officinale rhizome‐derived materials merit further study as potential T putrescentiae control agents or as lead compounds.

© 2002 Society of Chemical Industry
Mechanisms of resistance to organophosphorus insecticides in populations of the obliquebanded leafroller Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae) from southern Ontario
Authors: Pree David J , Whitty Karen J , Bittner Lori A , Pogoda Mitchell K
Published: December 2002

Populations of Choristoneura rosaceana (Harris) from orchards in Ontario were shown to be resistant to azinphos‐methyl and to other types of organophosphorus insecticides. Resistance extended to methyl carbamates and to methomyl. The laboratory population used for these assays and selected with azinphosmethyl was also resistant to the pyrethroid, cypermethrin. Resistance was associated with increased esterase activity and was reduced by the addition of the synergist DEF. IEF studies of esterases also indicated increased activity in resistant populations, but did not identify any unique esterases associated with the resistance. Resistance was highly correlated (r = 0.78) with elevated esterases but not with increased glutathione‐S transferase activity (r = 0.13). Other mechanisms did not appear to be related.

For the Department of Agriculture and Agri‐Food, Government of Canada, © Minister of Public Works and Government Services Canada 2002. Published for SCI by John Wiley & Sons, Ltd.
Isolation of a Pseudomonas fluorescens metabolite/exotoxin active against both larvae and pupae of vector mosquitoes
Authors: Prabakaran G , Paily K P , Padmanabhan V , Hoti S L , Balaraman K
Published: December 2002

A formulation was developed from the metabolite(s) of a novel Pseudomonas fluorescens Migula strain (VCRC B426) and tested against 4th‐instar larvae and pupae of three species of vector mosquitoes, Anopheles stephensi Liston, Culex quinquefasciatus Say and Aedes aegypti (L). The larvae and pupae of An stephensi were the most susceptible to the formulation, followed by those of C quinquefasciatus and Ae aegypti, in that order, and the dosage requirement for pupal mortality was less than that required for larval mortality. The LC50 dosage requirements for larvae of these mosquito species were, respectively, 70.4, 511.5 and 757.3 µg protein ml−1, whereas for pupae they were, respectively, 2.0, 9.4 and 19.2 µg protein ml−1. The lethal fraction was purified from the culture broth and its molecular mass, as determined by high performance liquid chromatography, was 44 kDa. This is the first report of a microbial formulation acting upon mosquito pupae, a non‐feeding stage. Its mode of action and efficacy to control mosquitoes under field conditions need to be studied further.

© 2002 Society of Chemical Industry
Susceptibility of field populations of adult Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) and Eretmocerus sp (Hymenoptera: Aphelinidae) to cotton insecticides in Burkina Faso (West Africa)
Authors: Otoidobiga Lenli C , Vincent Charles , Stewart Robin K
Published: December 2002

Research was conducted in 14 cotton fields (3–10 ha) selected in seven localities (two fields per locality) in Burkina Faso, with the objectives of: (1) estimating Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) population abundance, (2) assessing the levels of parasitism by Encarsia spp and Eretmocerus spp (Hymenoptera: Aphelinidae) and (3) estimating the susceptibilities of the pest and of an Eretmocerus sp to the insecticides currently sprayed on cotton. Yellow sticky cards and a leaf‐turning technique were used to estimate adult B tabaci population densities. Yellow sticky cards were also used to estimate the densities of adult Eretmocerus sp and the susceptibilities of B tabaci to insecticides. Leaf disk techniques were used to estimate B tabaci red eye nymph populations and parasitism by Encarsia spp and Eretmoceus spp was evaluated using stereo‐microscopy. A leaf cage technique was used to estimate the susceptibilities of Eretmocerus sp to insecticides. A mean of 6.5–27.4 adult B tabaci were trapped per yellow sticky card and 5.5 to >34.9 were counted per leaf using the leaf turning technique. There were 0.14–13 Eretmocerus sp trapped per yellow sticky card. The levels of parasitism varied between 36 and 87% by the end of the season and parasitism by Eretmocerus sp predominated in most of the fields. The susceptibilities of B tabaci and Eretmocerus sp varied from field to field and with the insecticide tested.

© 2002 Society of Chemical Industry
Diaryloxyacetate herbicides
Authors: Smith Michael G , Lo William C , Jacks Wendy , Moore Susan , Pernich Daniel J , Subramanian Mani V , Turner James A
Published: December 2002

The discovery and investigation of a novel family of herbicides containing a diaryl acetal are described. The stability of the acetal limited herbicidal efficacy and recognizing that fact led to the design of analogs with commercial levels of post‐emergence activity on broadleaf weeds. These compounds inhibited acetolactate synthase and in vitro activity data were used to guide target design. However, no members of this family provided a commercially valuable combination of herbicidal efficacy and crop selectivity.

© 2002 Society of Chemical Industry
Identification of the aromatase inhibitor aminoglutethimide in urine by gas chromatography/mass spectrometry
Authors: Mareck U. , Sigmund G. , Opfermann G. , Geyer H. , Schänzer W.
Published: December 2002

Aminoglutethimide is used therapeutically as an aromatase inhibitor in the treatment of metastatic breast cancer in post‐menopausal women. For doping purposes, aminoglutethimide may be used for treatment of adverse effects of an extensive abuse of anabolic androgenic steroids (gynaecomastia) and to increase the testosterone concentration and stimulation of testosterone biosynthesis. The use of aromatase inhibitors has been prohibited for male athletes since September 1, 2001. The purpose of this study was to develop methods for the identification of the parent compound or its main metabolite and the inclusion of this information into established screening procedures in doping analysis. An excretion study was conducted using oral application of one single therapeutic dose (500 mg) of Orimeten®. The analysis was performed by gas chromatography/mass spectrometry (GC/MS). Aminoglutethimide is excreted almost totally as unconjugated parent compound and is detectable by different screening procedures for up to 165 h. Most suitable for the detection of aminoglutethimide is the screening procedure for heavy volatile nitrogen‐containing drugs (‘Screening 2’). However, since only competition samples are analysed in that screening procedure, the additional inclusion of aminoglutethimide in the screening procedure for anabolic androgenic agents (‘Screening 4’) is recommended. Full mass spectra and diagnostic ions for the analysis of aminoglutethimide are presented. Copyright © 2002 John Wiley & Sons, Ltd.
Direct analysis of volatile organic compounds in human breath using a miniaturized cylindrical ion trap mass spectrometer with a membrane inlet
Authors: Riter Leah S. , Laughlin Brian C. , Nikolaev Eugene , Cooks R. Graham
Published: December 2002

Membrane introduction mass spectrometry (MIMS) coupled to a miniature mass spectrometer equipped with a cylindrical ion trap (CIT) analyzer was used to monitor the flavor components, 3‐phenyl‐2‐propenal and methyl salicylate, found in cinnamon and wintergreen candies, respectively, directly from human breath. The poly(dimethylsiloxane) (PDMS) membrane was operated in a trap‐and‐release mode, where the temperature of the membrane was cycled during the experiments, which permitted temporal resolution of the two compounds of interest, facilitating their observation in the complex sample. Under these thermally driven conditions, the 10–90% rise times for both compounds are similar (15 s for methyl salicylate, 17 s for 3‐phenyl‐2‐propenal), but the difference in diffusivity means that the signal for 3‐phenyl‐2‐propenal is delayed and the 10% point occurs 6 s later than that for wintergreen. Additional specificity needed for complex samples was gained by using tandem mass spectrometry. Copyright © 2002 John Wiley & Sons, Ltd.
Utility of three types of mass spectrometers for determining elemental compositions of ions formed from chromatographically separated compounds
Authors: Grange Andrew H. , Genicola Floyd A. , Sovocool G. Wayne
Published: December 2002

Concentration factors of 1000 and more reveal dozens of compounds in extracts of water supplies. Library mass spectra for most of these compounds are not available, and alternative means of identification are needed. Determination of the elemental compositions of the ions in mass spectra makes feasible searches of commercial and chemical literature that often lead to compound identification. Instrumental capabilities that constrain the utility of a mass spectrometer for determining ion compositions for compounds that elute from a chromatographic column are scan speed, mass accuracy, linear dynamic range, and resolving power. Mass peak profiling from selected ion recording data (MPPSIRD) performed with a double‐focusing mass spectrometer provides the best combination of these capabilities. This technique provides unique ion compositions for ions of higher mass from compounds eluting from a gas chromatograph than can be obtained by orthogonal acceleration time‐of‐flight (oa‐TOF) or Fourier transform ion cyclotron resonance mass spectrometry. Multiple compositions are usually possible for an ion with a mass exceeding 150 Da within the error limits of the mass measurement. The correct composition is selected based on measured exact masses of the mass peak profiles resulting from isotopic ions higher in mass by 1 and 2 Da and accurate measurement of the summed abundances of these isotopic ions relative to the monoisotopic ion. A profile generation model (PGM) automatically determines which compositions are consistent with measured exact masses and relative abundances. The utility of oa‐TOF and double‐focusing mass spectrometry using ion composition elucidation (MPPSIRD plus the PGM) are considered for determining ion compositions of two compounds found in drinking water extracts and a third compound from a monitoring well at a landfill. Published in 2002 by John Wiley & Sons, Ltd.
Gas chromatography/mass spectrometric study of non‐commercial C‐4‐substituted 1,4‐dihydropyridines and their oxidized derivatives
Authors: López‐Alarcón C. , Squella J. A. , Núñez‐Vergara Luis J. , Baez H. , Camargo Cristián
Published: December 2002

A gas chromatography/mass spectrometry (GC/MS) method for the qualitative and quantitative determination of the calcium‐channel antagonists C‐4‐substituted 1,4‐dihydropyridines, and their corresponding N‐ethyl derivatives, is presented. Also, the electrochemical oxidation and the reactivity of the compounds with alkyl radicals derived from 2,2′‐azobis‐(2‐amidinopropane) were monitored by GC/MS. Mass spectral fragmentation patterns for the C‐4‐substituted 1,4‐dihydropy‐ridine parent drugs were significantly different from those of their oxidation products, generated either by electrochemical oxidation or by reaction with alkyl radicals. However, for N‐ethyl‐1,4‐dihydropyridine compounds it was not possible to detect the final products (pyridinium salts) using these experimental conditions. Copyright © 2002 John Wiley & Sons, Ltd.
Liquid chromatography/electrospray tandem mass spectrometry characterization of styrene metabolism in man and in rat
Authors: Manini Paola , Andreoli Roberta , Poli Diana , De Palma Giuseppe , Mutti Antonio , Niessen Wilfried M. A.
Published: December 2002

Liquid chromatography with electrospray tandem mass spectrometry was used to characterize the metabolism of styrene in man and in rat. To improve identification and characterization of minor styrene metabolites, rats were co‐exposed to styrene and styrene‐d8. In addition to the main styrene metabolites, mandelic acid and phenylglyoxylic acid, and specific mercapturic acids, phenylhydroxyethylmercapturic acids (PHEMAs), other minor metabolites, including phenylglycine, N‐acetyl‐S‐(phenacyl)cysteine, 4‐vinylphenol and styreneglycol conjugates (glucuronides and sulfates) were identified and determined both in human and rat urine. Phenylglycine and N‐acetyl‐S‐(phenacyl)cysteine have been hypothesized to occur, but never detected in human or rat urine after styrene exposure. 4‐Vinylphenol and styrene glycol had already been recognized as styrene metabolites, but never determined as intact glucuronide and sulfate conjugates. Failure to identify 1‐ and 2‐phenylethanol conjugates suggests that phenylethanol might be an intermediate metabolite, but it is not a conjugated catabolite. A method for the simultaneous determination of mandelic acid, phenylglyoxylic acid, phenyglycine and the four PHEMA diastereoisomers has been developed and validated. For those glucuronide and sulfate conjugates whose standards are not commercially available, a method for semiquantitative analysis, based on the use of structurally similar compounds as standards, has been developed. This approach was found to be valid for the determination of 4‐vinylphenol glucuronide and 4‐vinylphenol sulfate. Copyright © 2002 John Wiley & Sons, Ltd.
Quantitative analysis using gas chromatography/combustion/isotope ratio mass spectrometry and standard addition of intrinsically labelled standards (SAIL) –application to isoflavones in foods
Authors: Bluck Leslie J. C. , Jones Kerry S. , Thomas Jane , Liggins Jason , Harding Marilyn , Bingham Sheila A. , Coward W. Andrew
Published: December 2002

We have investigated a novel application of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) for the quantitative analysis of the isoflavones in food matrices. Previous methods have been hampered by the lack of analytical standards to introduce early enough in the extraction procedure to allow compensations for losses at all stages of the procedure. In this work we have produced standard materials that can be added at the initial extraction, by intrinsically labelling soya plants by growing them in an atmosphere enriched in the stable isotope of carbon in CO2. On analysis these plants were shown to contain phytoestrogens at a high (up to 20%) level of enrichment. The dried plant material has been used to estimate the isoflavone concentrations of a set of spiked flours. For daidzein the methodology was shown to produce results comparable to those achieved by GC/MS techniques. The method was less successful for genistein, possibly due to the greater fragility of this compound under the conditions required for the analysis. Copyright © 2002 John Wiley & Sons, Ltd.
Studies on azaspiracid biotoxins. I. Ultrafast high‐resolution liquid chromatography/mass spectrometry separations using monolithic columns
Authors: Volmer Dietrich A. , Brombacher Stephan , Whitehead Bob
Published: December 2002

In this study, the performance of monolithic columns was evaluated for ultrafast liquid chromatography/mass spectrometry (LC/MS) analyses and for high‐resolution separations of several azaspiracid biotoxin analogs. Because of their high permeability, monolithic columns offer a number of advantages over conventional packed columns; viz., very low backpressures and relatively flat van Deemter curves at high flow rates. That is, very high flow rates can be used for ultrafast analyses or, by using longer than normal columns, high‐resolution separations are possible. In a series of experiments, we varied the mobile phase flow rates between 1 and 8 mL/min, and studied their impact on chromatographic parameters such as retention time, resolution, number of plates and pressure. The chromatographic run times could be reduced to ca. 30 s without a significant change in the separation efficiency. A signal intensity comparison revealed interesting differences between atmospheric‐pressure chemical ionization (APCI) and electrospray ionization (ESI) in their flow‐rate dependency. An explanation with respect to the behavior as of a mass‐flow or a concentration‐dependent device is given in the paper. Additionally, the column length was varied between 10 and 70 cm. As a result, the number of theoretical plates increased substantially. In the example shown in the report, an increase from 13 000 plates for a 10‐cm column to 80 000 for a 70‐cm column is demonstrated. In addition, the potential of the monolithic columns for high‐resolution LC/MS separations is shown for a complex biotoxin mixture, which was separated on a 40‐cm‐long column. Copyright © 2002 John Wiley & Sons, Ltd.
Investigation of the electrospray response of lysine‐, arginine‐, and homoarginine‐terminal peptide mixtures by liquid chromatography/mass spectrometry
Authors: Brancia Francesco L. , Openshaw Matthew E. , Kumashiro Sumio
Published: December 2002

Guanidination has been used to investigate how modification of the lysine η‐amino group into the corresponding guanidino group affects response in electrospray (ES) mass spectrometry (MS). Selected ion monitoring (SIM) analysis of equimolar mixtures containing arginine‐, lysine‐ and the corresponding homoarginine‐terminal peptides following liquid chromatography (LC) showed differences in ES response. The ionisation behaviour of the standard peptides is in accordance with the postulated higher stability of the guanidino group present on arginine‐ and homoarginine‐terminal peptides. Modification of the separation conditions employed during LC demonstrates that relative abundances of electrosprayed peptides ions rely mostly on peptide structure. Copyright© 2002 John Wiley & Sons, Ltd.
Polyaniline‐coated nanoelectrospray emitters: performance characteristics in the negative ion mode
Authors: Bigwarfe Paul M. , White Thomas P. , Wood Troy D.
Published: December 2002

The increasing tendency to miniaturize analytical techniques has resulted in the widespread use of nanoelectrospray ionization mass spectrometry. A new polyaniline‐coated nanoelectrospray emitter has shown increasing promise as a more durable and stable alternative to traditional metal‐coated emitters. In this report, the utility of polyaniline‐coated nanoelectrospray emitters in the negative ion mode is investigated. Here, oligonucleotides and peptides have been ionized in the negative mode using polyaniline‐coated nanoelectrospray emitters. The emitters were found to be durable for at least an hour in the negative ion mode, during which time the signal was stable. The high amount of electrical discharge usually associated with negative ion mode nanoelectrospray was not problematic with the polyaniline‐coated emitters. These characteristics make possible the reliable coupling of low‐flow separations to negative ion nanoelectrospray without the worry of emitter failure during the course of the experiment. Copyright © 2002 John Wiley & Sons, Ltd.
Gas chromatography/mass spectrometric characterisation of pyrolysis/silylation products of glucose and cellulose
Authors: Fabbri Daniele , Chiavari Giuseppe , Prati Silvia , Vassura Ivano , Vangelista Marta
Published: December 2002

The mass spectra of trimethylsilyl (TMS) derivatives of possible hydroxylated pyrolysis products of glucose and cellulose were recorded by gas chromatography/mass spectrometry (GC/MS) analyses of TMS derivatives of 2‐hydroxymethylfuran, 2‐hydroxy‐1‐methyl‐1‐cyclopenten‐3‐one, 5‐(hydroxymethyl)‐2‐furaldehyde, 5‐methyl‐2‐furoic acid, 4‐hydroxy‐6‐methyl‐(2H)‐pyran‐2‐one, 2‐methyl‐3‐hydroxy‐(4H)‐pyran‐4‐one (maltol) and 1,6‐anhydro‐β‐D‐glucopyranose (levoglucosan, LG). Also, 2‐O‐TMS‐1,6‐anhydro‐β‐D‐glucopyranose, 4‐O‐TMS‐1,6‐anhydro‐β‐D‐glucopyranose and 2,4‐bis‐O‐TMS‐1,6‐anhydro‐β‐D‐glucopyranose were identified from the interpretation of electron impact and chemical ionisation mass spectra of products obtained from partially silylated levoglucosan solutions, together with information from the known relative reactivities of OH groups of anhydrosugars. A peak at m/z 116 was found to be characteristic of the mass spectra of partially silylated anhydrosugars, and is absent from the mass spectra of the persilylated species. Pyrolysis/GC/MS of cellulose in the presence of hexamethyldisilazane afforded principally the 2‐ and 4‐TMS ethers and the 2,4‐bis‐TMS ether of LG, whereas the 5‐TMS‐oxymethyl‐2‐furaldehyde was a prominent pyrolysis/silylation product of glucose. The mass spectra of other relevant pyrolysis/silylation products are presented. Copyright © 2002 John Wiley & Sons, Ltd.
Electrospray ionization quadrupole time‐of‐flight mass spectrometry and quadrupole mass spectrometry for genotyping single nucleotide substitutions in intact polymerase chain reaction products in K‐ras and p53
Authors: Muhammad Warees T. , Fox Karen F. , Fox Alvin , Cotham William , Walla Michael
Published: December 2002

Single nucleotide polymorphisms (SNPs) and mutations were genotyped for both homozygous and heterozygous PCR products of p53, a tumor suppressor gene, and K‐ras, an oncogene, using electrospray ionization (ESI) quadrupole time‐of‐flight (Q‐TOF) mass spectrometry (MS) and ESI‐quadrupole MS analysis. Mass accuracy was adequate for both instruments to detect genetic changes in homozygous PCR products, including the most difficult to distinguish (adenine [A] → thymine [T] transversion). However, for the detection of A → T shifts (9.0 Da difference) in heterozygous PCR products, the increased resolution of ESI‐Q‐TOFMS proved essential. Although, greater mass differences in heterozygotes (e.g. cytosine [C] ↔ T or guanine [G] ↔ A) can be discriminated using ESI‐quadrupole MS analysis. Copyright © 2002 John Wiley & Sons, Ltd.
Differentiation of the geographical origin of durum wheat semolina samples on the basis of isotopic composition
Authors: Brescia M. A. , Di Martino G. , Guillou C. , Reniero F. , Sacco A. , Serra F.
Published: December 2002

The identification of the geographical origin of foods is attracting great interest from consumers and producers since it may be used as a criterion for guaranteeing quality and authenticity. Stable isotope techniques can provide useful information on the origin of food products. The natural abundance isotopic ratios of carbon, oxygen and nitrogen were determined and a comparison made between the isotopic content of samples originating from Italy and those of samples originating from other countries (Canada, Turkey, Australia). A correlation was found between the isotopic composition and geographical origin of the samples. The relationship between isotopic content and the latitude has been confirmed. Copyright © 2002 John Wiley & Sons, Ltd.
Optimization of a liquid chromatography method based on simultaneous electrospray ionization mass spectrometric and ultraviolet photodiode array detection for analysis of flavonoid glycosides
Authors: Cuyckens Filip , Claeys Magda
Published: December 2002

Different reversed‐phase liquid chromatography (LC) columns of conventional dimensions were coupled to an ultraviolet photodiode array detector (UV‐DAD) and a magnetic sector‐type spectrometer, equipped with an electrospray ionization (ESI) source, by a laboratory‐made flow splitter. A mixture of three flavonoid‐O‐glycosides was employed to examine the effects of the solvent composition, the flow rate, the stationary phase, the pH and the organic acid added, on the chromatographic separation, the UV‐DAD detection, the ESI process and the entire LC system with ESI‐MS and UV‐DAD detection. In the positive ion mode, methanol containing 1% acetic acid was by far the most sensitive in ESI‐MS analysis, whereas an acetonitrile/water mobile phase containing 0.5% formic acid was proved to give the best sensitivity in LC/ESI‐MS/UV‐DAD analysis. In the negative ion mode, the highest sensitivity was obtained with a mobile phase containing 0.1% formic acid, while addition of bases decreased the sensititvity. The optimal flow rate was higher in negative ESI (20–50 µL/min) than in positive ESI (5 µL/min), and the percentage of organic phase had an influence on the sensitivity of ESI‐MS detection. With regard to the selection of a suitable C18 reversed‐phase LC column, a column which is well end‐capped is to be preferred, because residual silanol groups appear to impair the separation of flavonoid glycosides. The optimized LC/ESI‐MS/UV‐DAD method was applied to a commercial Crataegus extract, which is used in phytomedicine to treat cardiovascular problems and is known to be rich in flavonoids. It is demonstrated how UV spectra and first‐order ESI mass spectra allow a fast characterization of flavonoids, even if reference compounds are not available or at hand. Copyright © 2002 John Wiley & Sons, Ltd.
Differentiation of vegetable oils by mass spectrometry combined with statistical analysis
Authors: Jakab A. , Nagy K. , Héberger K. , Vékey K. , Forgács E.
Published: December 2002

The main triacylglycerol (TAG) composition of different plant oils (almond, avocado, corn germ, grape seed, linseed, mustard seed, olive, peanut, pumpkin seed, sesame seed, soybean, sunflower, walnut and wheat germ) were analyzed using two different mass spectrometric techniques: HPLC/APCI‐MS (high‐performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry) and MALDI‐TOFMS (matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry).

Linear discriminant analysis (LDA) as a multivariate mathematical statistical method was successfully used to distinguish different plant oils based on their relative TAG composition. With LDA analysis of either APCI‐MS or MALDI‐MS data, the classification among the almond, avocado, grape seed, linseed, mustard seed, olive, sesame seed and soybean oil samples was 100% correct. In both cases only 6 different oil samples from a total of 73 were not classified correctly. Copyright © 2002 John Wiley & Sons, Ltd.
Studies on azaspiracid biotoxins. II. Mass spectral behavior and structural elucidation of azaspiracid analogs
Authors: Brombacher Stephan , Edmonds Suzanne , Volmer Dietrich A.
Published: December 2002

In this report, the mass spectral analysis of azaspiracid biotoxins is described. Specifically, the collision‐induced dissociation (CID) behavior and differences between CID spectra obtained on a triple‐quadrupole, a quadrupole time‐of‐flight, and an ion‐trap mass spectrometer are addressed here. The CID spectra obtained on the triple‐quadrupole mass spectrometer allowed the classification of the major product ions of the five investigated compounds (AZA 1–5) into five distinct fragment ion groups, according to the backbone cleavage positions. Although the identification of unknown azaspiracids was difficult based on CID alone, the spectra provided sufficient structural information to allow confirmation of known azaspiracids in marine samples. Furthermore, we were able to detect two new azaspiracid analogs (AZA 1b and 6) in our samples and provide a preliminary structural analysis. The proposed dissociation pathways under tandem mass spectrometry (MS/MS) conditions were confirmed by a comparison with accurate mass data from electrospray quadrupole time‐of‐flight MS/MS experiments. Regular sequential MS
n analysis on an ion‐trap mass spectrometer was more restricted in comparison to the triple‐quadrupole mass spectrometer, because the azaspiracids underwent multiple [M + H − nH2O]+ (n = 1–6) losses from the precursor ion under CID. Thus, the structural information obtained from MS
n experiments was somewhat limited. To overcome this limitation, we developed a wide‐range excitation technique using a 180‐u window that provided results comparable to the triple‐quadrupole instrument. To demonstrate the potential of the method, we applied it to the analysis of degraded azaspiracids from mussel tissue extracts. Copyright © 2002 John Wiley & Sons, Ltd.
N‐Terminal peptide labeling strategy for incorporation of isotopic tags: a method for the determination of site‐specific absolute phosphorylation stoichiometry
Authors: Zhang Xiaolong , Jin Qian K. , Carr Steven A. , Annan Roland S.
Published: December 2002

Determining the phosphorylation stoichiometry at specific sites in a phosphoprotein is a very challenging task. We describe here a novel mass spectrometry based method that is capable of measuring the absolute phosphorylation stoichiometry at specific sites without the need for specific internal standards, phospho‐site antibodies or radioactivity. The method is based on a gentle chemical labeling strategy which specifically and differentially labels the N‐terminus of all peptides in a sample with either a D5‐ or D0‐propionyl group and measures the ratio of the abundance of the D5/D0 peptide pairs simultaneously using mass spectrometry. Using matrix‐assisted laser desorption/ionization (MALDI), the method can measure absolute stoichiometry to within at least 10% and can be applied to both in vitro and in vivo phosphorylated peptides and proteins. Furthermore, this method can potentially be applied to the quantitative study of other types of protein post‐translational modifications, and the profiling of protein expression on the proteome level. Copyright © 2002 John Wiley & Sons, Ltd.
A new sheathless electrospray interface for coupling of capillary electrophoresis to ion‐trap mass spectrometry
Authors: Bendahl Lars , Hansen Steen Honoré , Olsen Jørgen
Published: December 2002

A simple laboratory‐made sheathless electrospray interface for coupling of capillary electrophoresis to ion‐trap mass spectrometry (CE/MS) was developed. The interface was machined in‐house and it was designed to be freely interchangeable with the commercially available ionization sources for the mass spectrometer. Sharpened fused‐silica capillaries were coated with nickel by a simple electrodeless plating procedure and were used as all‐in‐one columns/emitters. The electrodeless plating produced a 2–5‐µm thick smooth nickel layer that lasted for more than 8 h of continuous electrospraying. The performance of the CE/MS interface was examined by using four cationic imipramine derivatives as test substances. Relative detection limits were calculated on the basis of the extracted ion electrophorograms and were in the range 6–130 nmol/L, corresponding to absolute detection limits in the range of 20–400 amol. The system was applied for analysis of impurities in an impure imipramine N‐oxide preparation, and two of the impurities could be identified on the basis of online‐MS(MS) spectra recorded in scan‐dependent mode. Copyright © 2002 John Wiley & Sons, Ltd.
Structural confirmation of ostreocin‐D by application of negative‐ion fast‐atom bombardment collision‐induced dissociation tandem mass spectrometric methods
Authors: Ukena Takanori , Satake Masayuki , Usami Masaya , Oshima Yasukatsu , Fujita Tsuyoshi , Naoki Hideo , Yasumoto Takeshi
Published: December 2002

Negative‐ion fast‐atom bombardment collision‐induced dissociation tandem mass spectrometric (FAB‐CID‐MS/MS) methodology was successfully applied to verify the highly complex structure of ostreocin‐D (MW 2633), a new palytoxin analog isolated from the marine dinoflagellate Ostreopsis siamensis and proposed to be 42‐hydroxy‐3,26‐didemethyl‐19,44‐dideoxypalytoxin based on NMR data. The charge‐remote fragmentations were facilitated by a negative charge introduced to a terminal amino group or to a hydroxyl group at the other terminus by a reaction with 2‐sulfobenzoic acid cyclic anhydride. Product ions generated from the [M − H]− ions provided information on the structural details of ostreocin‐D. Comparisons between the spectral data for ostreocin‐D and palytoxin also provided a rational basis for the assignments of product ions. Copyright © 2002 John Wiley & Sons, Ltd.
Reactions of lead cluster ions with acetone
Authors: Tian Zhixin , Xing Xiaopeng , Tang Zichao
Published: December 2002

Reactions of lead cluster cations and anions with acetone have been studied using a homemade reflectron time‐of‐flight mass spectrometer. Association with acetone to form Pbk(CH3COCH3)n+, high‐energy pathway reactions forming PbkCH3+, and intraheterocluster reaction of Pbk(CH3COCH3)n+1+ to give PbkCH3(CH3COCH3)n+ were the main reaction pathways for lead cluster cations with acetone. Decomposition of acetone by Pbk− to give PbkCm− ions and their further association with acetone, PbkCm(CH3COCH3)−, were the dominant reactions of lead cluster anions with acetone. Pb7−, Pb10−, and PbkC5− were ‘magic numbers’ with special structural stabilityin Pbk− and PbkCm−, respectively. In addition, PbkH−, CH2COCH3(CH3COCH3)n− and PbkCH2COCH3(CH3COCH3)n− were also observed in the reaction of lead cluster anions. Some reaction mechanisms are proposed for these reactions. To investigate the isotope effect for the reaction of lead cluster cations and anions with acetone and to verify the structural assignments of the observed ions, reactions of lead cluster cations and anions with deuterated acetone‐d6 were also performed. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of proanthocyanidins in grape seeds using electrospray mass spectrometry
Authors: Hayasaka Yoji , Waters Elizabeth J. , Cheynier Véronique , Herderich Markus J. , Vidal Stéphane
Published: December 2002

Two proanthocyanidin (PA) fractions, one (Sdp3) with the mean degree of polymerization (mDP) of 3 and the other (Sdp9) with mDP of 9, were obtained from a Vitis vinifera cv. Shiraz grape seed extract. The PA fractions were directly analyzed by electrospray ionization mass spectrometry (ES‐MS) and negative ion mass spectra were recorded. The mass spectrum of Sdp3 exhibited only singly charged ions corresponding to the molecular mass of PA with a degree of polymerization (DP) up to 9 (nonamers). In contrast, Sdp9 yielded rather complex mass spectra featuring ions with single [M − H]−, double [M − 2H]2− and triple [M − 3H]3− charge representing the molecular masses of PAs up to a DP of 28. In addition, the degree of galloylation per procyanidin (DG) was observed to be up to 5 (pentagallates) in Sdp3 and 8 (octagallates) in the Sdp9. This is the first evidence obtained by mass spectrometry for the distribution of grape seed PAs with such a high degree of polymerization and a broad diversity of galloylation. ES‐MS data together with the complementary information provided by acid hydrolysis provides a detailed picture of the composition of grape seed PAs. Copyright © 2002 John Wiley & Sons, Ltd.
Positive and negative gas‐phase ion chemistry of chlorofluorocarbons in air at atmospheric pressure
Authors: Bosa Elisabetta , Paradisi Cristina , Scorrano Gianfranco
Published: December 2002

This paper presents a report on the ionization/dissociation of some representative chlorofluoro‐carbons (CFCs) induced by corona discharges in air at atmospheric pressure. Both positive and negative ions formed from Freons 1,1,1‐trichlorotrifluoroethane (CFC 113a), 1,1,2‐trichlorotrifluoroethane (CFC 113), and 1,1,1,2‐tetrachlorodifluoroethane (CFC 112a) were analyzed using an atmospheric pressure chemical ionization mass spectrometry (APCI‐MS) instrument. Energy‐resolved mass spectra were obtained by modulating the kinetic energy of the ions via adjustment of the sampling cone potential (Vcone). Positive ion spectra of the CFCs (M) at low Vcone show no signals due to either M+· or MH+ but only those due to species [M − Cl]+ and CX3+ (X = Cl, F), likely formed via C–Cl and C–C bond cleavages following ionization via charge exchange. Charge localization in the products of C–C bond cleavage in M+· is driven by the stability of the neutral fragment. At low Vcone the hydrates [M − Cl]+(H2O) are also observed. In the case of 1,1,2,‐trichlorotrifluoroethane, [M − F]+ species also form as a result of ion‐molecule reactions. As Vcone is increased collision‐induced dissociation of [M − Cl]+ and [M − F]+, i.e., the perhalogenated cations C2X5+ (X = Cl, F), takes place via carbene elimination. In some cases such elimination is preceded or accompanied by rearrangements involving transfer of halogen from one carbon to the other. Evidence is also presented for the occurrence of a condensation reaction of C2Cl3F2+ with water to form a C2Cl2F2HO+ species via elimination of HCl. Negative ion spectra are dominated by Cl− and its ion‐neutral complexes with M and with water. Additional components of the plasma include ion‐neutral complexes O3−(M), the molecular anion M− (observed only with 1,1,2‐trichlorotrifluoroethane), and an interesting species corresponding to [M − Cl + O]−. The origin and structure of these [M − Cl + O]− species are discussed in terms of available thermochemical and reactivity data and current mechanistic views concerning reaction of O2− with halogenated compounds. The observation of both positive and negative ions containing oxygen is of special relevance to development of new processes for the treatment of volatile organic compounds (VOCs) based on oxidative decomposition induced by corona discharges in air at room temperature and pressure. Copyright © 2002 John Wiley & Sons, Ltd.
Characterisation of putative pentose‐containing conjugates as minor metabolites of 4‐bromoaniline present in the urine of rats following intraperitoneal administration
Authors: Major Hilary , Castro‐Perez Jose , Nicholson Jeremy K. , Wilson Ian D.
Published: December 2002

The metabolic fate of 4‐bromoaniline (4‐BrA) was investigated following intraperitoneal administration to the rat at 50 mg kg−1, using high‐performance liquid chromatography/time‐of‐flight tandem mass spectrometry (HPLC/TOF‐MS/MS). Up to five metabolites were detected in urine that correspond to isomeric pentose conjugates (possibly ribosides) of a hydroxysulphate of 4‐BrA. This identification is supported by further studies where the water used in the reversed‐phase solvent system was replaced with deuterated water in order to confirm that the number of exchangeable protons present in the metabolites was consistent with the proposed structures. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis of ceramides in cosmetics by reversed‐phase liquid chromatography/electrospray ionization mass spectrometry with collision‐induced dissociation
Authors: Lee Myoung Hee , Lee Gae Ho , Yoo Jong Shin
Published: December 2002

A rapid, sensitive and selective method involving reversed‐phase liquid chromatography (LC) with electrospray ionization (ESI) mass spectrometry (MS) was employed for determination of commercial ceramides in cosmetics for quality control of the product formulation. Using this LC/ESI‐MS technique, simultaneous separation and characterization of ceramides and an impurity substance were possible. Informative fragmentation patterns were obtained by employing LC/ESI‐MS in both positive and negative ionization modes to identify the structures of both sphingoid base and N‐acyl chains of ceramides, and also of an impurity. The combination of positive and negative mass spectra can be used for unambiguous confirmation of ceramides and for characterization of unknown species. In‐source collision‐induced fragmentation resulted in characteristic product anions for the ceramides containing a phytosphingosine moiety at m/z 267, 255 and 225, and for those with a sphingosine moiety at m/z 263 and 237, regardless of the length of the fatty acyl chains. The detection limit was about 0.5 pmol in selected‐ion monitoring mode. Quantification using internal standards showed good linearity and a relative standard deviation of 4%. These ceramides were more sensitively detected in positive than in negative ion mode. Copyright © 2002 John Wiley & Sons, Ltd.