Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Glutenvrij ? Pils onde de loep
    Sleutels, I. ; Meer, I.M. van der; Broeck, H.C. van den - \ 2014
    Voedingsmiddelentechnologie 7 (2014). - ISSN 0042-7934 - p. 10 - 11.
    gluten - coeliakie - glutenvrije diëten - bieren - alcoholische dranken - gerst - lc-ms - analytische methoden - coeliac syndrome - gluten free diets - beers - alcoholic beverages - barley - liquid chromatography-mass spectrometry - analytical methods
    Gluten meten in gehydrolyseerde en gefermenteerde voedingsmiddelen – zoals pils – is lastig. De door de Codex Alimentarius gevalideerde test onderschat het gehalte gluten in deze producten. Een uitgebreide LC-MS/MS-analyse geeft gedetailleerde informatie over de aanwezige coeliakie-stimulerende gluten in pils. Met deze gegevens is een geschikte test te ontwikkelen.
    LC-MS residue analysis of antibiotics : what selectivity is adequate?
    Berendsen, B.J.A. - \ 2013
    Wageningen University. Promotor(en): Michel Nielen, co-promotor(en): Linda Stolker. - S.l. : s.n. - ISBN 9789461735690 - 352
    antibiotica - bèta-lactam antibiotica - chlooramfenicol - ceftiofur - voedselanalyse - lc-ms - selectiviteit - antibioticumresiduen - antibiotics - beta-lactam antibiotics - chloramphenicol - ceftiofur - food analysis - liquid chromatography-mass spectrometry - selectivity - antibiotic residues

    In residue analysis of antibiotics quantitative and qualitative aspects are involved in declaring a sample non-compliant. The quantitative aspect regards the determination of the amount of the compound present in the sample. Validation procedures are available to determine the uncertainty of this result, which is taken into account in the decision making process. The qualitative aspect regards the confirmation of the identity of the compound present. In this, selectivity is the main parameter which is defined as the ability of a method to discriminate the analyte being measured from other substances. A trend observed in residue analysis is towards more generic methods for the detection of a broad range of compounds in a single run. As a result, by definition, selectivity is compromised. Procedures to determine the uncertainty of the qualitative aspect are lacking and, as a result, whether or not a method is adequately selective is a matter of experts’ judgment.

    In this thesis a method is presented for grading selectivity of methods using liquid chromatography coupled to tandem mass spectrometry. Based on the outcome it can be stated if selectivity is adequate and thus if a confirmatory result stands strong when challenged in a court case. If selectivity is found inadequate, additional measures can be taken like the selection of another product ion or the use of a third product ion to obtain adequate selectivity.

    Furthermore, two examples of analyses are presented in which selectivity plays an important role. First, the analysis of the banned antibiotic chloramphenicol (CAP). CAP contains two chiral centers and the nitro-group can either be para- or meta-substituted. Therefore, eight different isomers of CAP occur of which only RR-p-CAP is antimicrobially active. In the analysis of CAP, extreme selectivity is needed to distinguish the antimicrobially active compound from its inactive isomers. A method applying chiral liquid chromatography with tandem mass spectrometry was developed to discriminate antimicrobially active CAP for its inactive isomers. Also the research for the possible natural occurrence of this drug is presented. It is shown that CAP can be produced in unamended soil by Streptomyces venezuelaein appreciable amounts and that crops can take up CAP from soils. Therefore, it is concluded that CAP can occur in crops and animal feed due to its natural production by soil bacteria.

    Second, the development of a multi-ß-lactam method is presented. In this method a derivatization is applied to be able to effectively detect off-label ceftiofur use. In this selectivity is intentionally compromised and no unequivocal confirmation can be carried out using this method. The developed method is applicable to a wide range of ß-lactam antibiotics including penicillins, cephalosporins and carbapenems and is the best method available today for effective monitoring of off-label ß-lactam usage in poultry breeding.

    Phomopsin A in lupin flour and lupin-containing food in the Netherlands
    Nijs, W.C.M. de; Pereboom-de Fauw, D.P.K.H. ; Rijk, T.C. de; Mol, J.G.J. - \ 2012
    - p. 1819 - 1826.
    phomopsinen - mycotoxinen - lupinen - voedselveiligheid - lc-ms - phomopsins - mycotoxins - lupins - food safety - liquid chromatography-mass spectrometry
    Survey on the occurrence of phomopsin A in lupin flour and lupin containing foods using an LC-MS/MS method.
    Phomopsin A in food samples in The Netherlands
    Nijs, W.C.M. de; Pereboom-de Fauw, D.P.K.H. ; Rijk, T.C. de; Egmond, H.J. van; Mol, J.G.J. - \ 2011
    mycotoxinen - phomopsinen - lupinen - lc-ms - voedselveiligheid - mycotoxins - phomopsins - lupins - liquid chromatography-mass spectrometry - food safety
    Phomopsin A (PHA) is a mycotoxin, mainly occurring in lupin. A straightforward LC/MS-MS method has been developed to investigate several lupin-containing food products available in the Netherlands.
    Quantitative determination of marine lipophilic toxins in shellfish using LC-MS/MS : international validation study - final report
    Top, H.J. van den; Gerssen, A. ; Egmond, H.P. van - \ 2011
    Wageningen : RIKILT (Report / Rikilt 2011.008)
    bepaling - kwantiteitscontrole - mariene biologie - toxinen - schaaldieren - lc-ms - determination - quantity controls - marine biology - toxins - shellfish - liquid chromatography-mass spectrometry
    The analysis of lipophilic marine toxins : development of an alternative method
    Gerssen, A. - \ 2010
    Wageningen University. Promotor(en): Ivonne Rietjens; J. de Boer, co-promotor(en): Patrick Mulder. - [S.l. : S.n. - ISBN 9789085857198 - 199
    toxinen - marien milieu - algen - alternatieven voor dierproeven - lc-ms - toxins - marine environment - algae - animal testing alternatives - liquid chromatography-mass spectrometry

    Lipophilic marine toxins are produced by certain algae species and can accumulate in filter feeding shellfish such as mussels, scallops and oysters. Consumption of contaminated shellfish can lead to severe intoxications such as diarrhea, abdominal cramps and vomiting. Methods described in European Union (EU) legislation to test for the presence of these toxins are based on a mouse or rat bioassay. These assays are unethical and have a poor sensitivity and selectivity. The aim of this thesis is to develop an alternative method based on liquid chromatography - tandem mass spectrometry (LC-MS/MS) for the quantitative analysis of lipophilic marine toxins.
    LC-MS/MS methods described in literature for the determination of lipophilic marine toxins used an acidic chromatographic system. Under acidic conditions peak shape and separation of a number of toxins preferably analyzed in electrospray ionization negative (ESI–) and positive (ESI+) were poor. A LC-MS/MS method with alkaline chromatographic conditions in which we were able to analyze 28 different toxins in a single analysis in separated retention time windows operating in either ESI– or ESI+ was developed. Furthermore, a clean up procedure based on solid phase extraction (SPE) was developed to reduce the amount of matrix effects (ion suppression and enhancement). A combination of SPE clean up and alkaline chromatographic conditions resulted in reduced matrix effects for all matrices tested (mussel, scallop and oyster).
    The developed SPE & LC-MS/MS method was in-house validated at regulatory limits based on EU Commission Decision 2002/657/EC. With respect to accuracy, repeatability, reproducibility, decision limit, specificity and ruggedness the method performed well. The method also performed excellently in view of possible new limits that are four- to five-fold lower than current limits for some toxins.
    Finally a screening method based on LC orbitrap MS was developed for 85 marine toxins of which most are not stated in EU legislation. The screening used in-house developed software which made it possible to reduce the complex data files and screen for a large number of toxins within seconds.
    This thesis will contribute to the replacement of the animal assays that are still prescribed in EU legislation for the determination of lipophilic marine toxins in shellfish.

    Metabolomics technologies applied to the identification of compounds in plants : a liquid chromatography-mass spectrometry - nuclear magnetic resonance perspective over the tomato fruit
    Moco, S.I.A. - \ 2007
    Wageningen University. Promotor(en): Raoul Bino; Sacco de Vries, co-promotor(en): Jacques Vervoort; Ric de Vos. - [S.l.] : S.n. - ISBN 9789085047421 - 222
    solanum lycopersicum - tomaten - metabolieten - fytochemicaliën - kernmagnetische resonantiespectroscopie - metabolomica - lc-ms - solanum lycopersicum - tomatoes - metabolites - phytochemicals - nuclear magnetic resonance spectroscopy - metabolomics - liquid chromatography-mass spectrometry
    A new era of plant biochemistry at the systems level is emerging in which the detailed description of biochemical phenomena, at the cellular level, is important for a better understanding of physiological, developmental, and biomolecular processes in plants. This emerging field is oriented towards the characterisation of small molecules (metabolites) that act as substrates, products, ligands or signalling entities in cells. This thesis concerns the development and establishment of such metabolomics strategies for screening and identifying metabolites in biological systems. Most technological strategies were applied to the assignment of metabolites from tomato (Solanum lycopersicum) fruit. Tomato was chosen for being a widely consumed crop with nutritional attributes, representing a model for the Solanaceae family. In order to achieve both high coverage of detected metabolites and valuable information for identification purposes, liquid chromatography coupled to mass spectrometry (LC-MS) and nuclear magnetic resonances (NMR) technologies were used. In addition, metabolite databases, based on experimental data (mass-based, in the case of LC-MS and chemical shift-based, in the case of NMR) were initiated, in order to systemize the extensive metabolite information. The chapters in this thesis describe method developments and their applications in plant metabolomics that are also feasible to be implemented on other biological systems. A review on the technologies used for metabolomics with a perspective on compound identification is presented in Chapter 1. In Chapter 2, a robust large scale LC-MS method for the analysis of metabolites in plants is described in detail. It presents a step-by-step protocol with thorough information about the reagents used, sample preparation, instrument set­up, methods of analysis and data processing strategies. The described analytical method combines LC with photo diode array (PDA) and MS detection, and allows the analysis of mostly semi-polar secondary metabolites present in plants, such as phenolic acids, flavonoids, glucosinolates, saponins, alkaloids and derivatives thereof. Chapter 3 presents an application of the LC-PDA-MS method for the profiling of metabolites present in tomato fruit. The metabolites putatively identified in this fruit were included in a tomato dedicated-database (the MoTo DB) that is available for public search on the web (see: http://appliedbioinformatics.wur.nl). A comparison between two tomato fruit tissues, peel and flesh, for their metabolite content was made using this MoTo DB. Using the same LC-PDA-MS setup, several different tomato fruit tissues were compared in more detail, along the fruit ripening timeline, in Chapter 4. The presence of tissue-specific metabolites, at determined ripening stages, suggests developmental control of metabolite biosynthesis. Such tissue-specific metabolomics approach may give rise to a biological view over metabolite compartmentalisation. Chapters 5 and 6 describe the implementation of a NMR database for secondary metabolites, mostly including flavonoids, the Flavonoid Database (see: Flavonoid Database under http://www.wnmrc.nl). The acquisition of a large data set of related standard compounds allowed the analysis of shifts in NMR characteristics by the presence of certain functional groups or substituents in the flavonoid backbone. In addition, a 1H NMR-based prediction model was iteratively trained from the acquired experimental data and can be used for the prediction of unknown related molecules. This approach greatly increases the efficiency in the identification of (flavonoid) metabolites. Chapter 7 describes correlations of metabolomics data derived from LC-MS and NMR analyses of a large number of different tomato cultivars. The identification of metabolites is obtained among other available sources, the MoTo DB and the Flavonoid Database. This approach illustrates the complementariness and coincidence of NMR and MS as analytical techniques, applied to the detection of metabolites in tomato fruit. The summarizing discussion and conclusions, sets the work presented in this thesis into a biochemical perspective, and prospects suggestions for the future.
    Gehaltebepaling van T2816 in waterige oplossingen met behulp van LC-MS
    Rhijn, J.A. van - \ 1993
    Wageningen : RIKILT-DLO (Rapport / RIKILT 93.01) - 16
    oppervlaktespanningsverlagende stoffen - analytische methoden - lc-ms - analytische scheikunde - surfactants - analytical methods - liquid chromatography-mass spectrometry - analytical chemistry
    Ontwikkelen van een massaspectrometrische confirmatie methode voor het aantonen van chlooramphenicol in vlees
    Kienhuis, P.G.M. ; Traag, W.A. ; Aerts, M.M.L. ; Tuinstra, L.G.M.Th. - \ 1988
    Wageningen : RIKILT (Rapport / RIKILT 88.40) - 12
    chlooramfenicol - vlees - bevestigingstesten - massaspectrometrie - lc-ms - gc-ms - vloeistofchromatografie - hplc - analytische methoden - chloramphenicol - meat - confirmatory tests - mass spectrometry - liquid chromatography-mass spectrometry - gc-ms - liquid chromatography - hplc - analytical methods
    In de EEG zijn onlangs een aantal criteria opgesteld, waaraan voldaan moet worden bij massaspectrametrische analyses, waarbij naast criteria voor de retentietijd, criteria voor het aantal te meten ionen, in relatie tot de ionisatietechniek worden gegeven. Op verzoek van de afdeling diergeneesmiddelen is recentelijk, onder andere in verband met een Nationaal plan en de algemene wens om bij de uitvoeringen van bepalingen met een wettelijke grondslag een confirmatiemethode ter beschikking te hebben, het onderzoek weer opgepakt. Onderzoek is verricht naar een aantal aspecten om te komen tot een goede confirmatie methode. Aandacht is gegeven aan het maken van derivaten, zowel met als zonder matrix, de uniekheid van de bijbehorende spectra, het opwerken van HPLC fracties welke chlooramphenicol bevatten, de lineariteit en reproduceerbaarheld van de GC-MS bij verschillende ionisatie-technieken en -omstandigheden. Parallel aan dit onderzoek zijn er experimenten uitgevoerd met de solid probe, waarbij chlooramphenicol, in vaste vorm , direct via een probe in de bron is gebracht. Ook is er onderzoek verricht naar de toepassing van LC-MS met betrekking tot chlooramphenicol. De resultaten van bovengenoemd onderzoek zullen t.z.t. apart worden gerapporteerd.
    Ontwikkeling van een FAST-LC methode voor een aantal nitrofuranen in ei
    Beek, W.M.J. ; Aerts, M.M.L. - \ 1986
    Wageningen : RIKILT (Rapport / RIKILT 86.73) - 5
    nitrofuranen - eieren - lc-ms - vloeistofchromatografie - nitrofurans - eggs - liquid chromatography-mass spectrometry - liquid chromatography
    Doel van dit onderzoek was: Het bepalen en/of screenen van de belangrijkste nitrofuranen in ei met behulp van FAST-LC op een meetniveau van 10 ppb. Er is een FAST-LC methode voor nitrofurantoine, nitrofurazon, furazolidon en furaltadon in ei ontwikkeld. Evenals bij vlees en melk worden door toepassing van het FAST-LC systeem monsters "on-line" automatisch geanalyseerd.
    Overzicht stand van zaken m.b.t. het ontwikkelen van analysemethoden voor het bepalen van enkele hormonen m.b.v. GC-MS
    Traag, W.A. ; Keukens, H.J. ; Tuinstra, L.G.M.Th. ; Ruig, W.G. de - \ 1982
    Wageningen : RIKILT (Verslag / RIKILT 82.80) - 17
    hormonen - gaschromatografie - lc-ms - massaspectrometrie - urine - urine-analyse - diagnostische technieken - hormones - gas chromatography - liquid chromatography-mass spectrometry - mass spectrometry - urine - urine analysis - diagnostic techniques
    Het vastleggen van enkele relevante gegevens voor de gaschromatografie- massaspectrometrische analyse van hormonen i.v.m. de bepaling in urine. Een achttal anabole stoffen zijn geselecteerd als zijnde mogelijke verbindingen welke in de toekomst met behulp van GC-MS onderzocht zullen moeten worden. Uitgegaan is van de in een eerder stadium ontwikkelde methode voor de bepaling van Diethylstilbestrol in runderurine. Teneinde na te gaan of deze methode geschikt is als multimethode en zo neen welke modificaties toegepast dienen te worden zijn alle facetten van de eerder beschreven methode (81.61) nagewerkt. Aanwijzingen, welke moeten leiden tot een zo'n uitgebreid mogelijke multimethode, worden gegeven.
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