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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    Touching the High Complexity of Prebiotic Vivinal Galacto-oligosaccharides Using Porous Graphitic Carbon Ultra-High-Performance Liquid Chromatography Coupled to Mass Spectrometry
    Logtenberg, Madelon J. ; Donners, Kristel M.H. ; Vink, Jolien C.M. ; Leeuwen, Sander S. van; Waard, Pieter de; Vos, Paul de; Schols, Henk A. - \ 2020
    Journal of Agricultural and Food Chemistry 68 (2020)29. - ISSN 0021-8561 - p. 7800 - 7808.
    galacto-oligosaccharides - liquid chromatography - porous graphitic carbon - preparative chromatography - tandem mass spectrometry

    Galacto-oligosaccharides (GOS) are used in infant formula to replace the health effects of human milk oligosaccharides, which appear to be dependent upon the structure of the individual oligosaccharides present. However, a comprehensive overview of the structure-specific effects is still limited as a result of the high structural complexity of GOS. In this study, porous graphitic carbon (PGC) was used as the stationary phase during ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS). This approach resulted in the recognition of more than 100 different GOS structures in one single run, including reducing and non-reducing GOS isomers. Using nuclear magnetic resonance-validated structures of GOS trisaccharides, we discovered MS fragmentation rules to distinguish reducing isomers with a mono- and disubstituted terminal glucose by UHPLC-PGC-MS. UHPLC-PGC-MS enabled effective recognition of structural features of individual GOS components in complex GOS preparations and during, e.g., biological conversion reactions. Hence, this study lays the groundwork for future research into structure-specific health effects of GOS.

    A critical assessment of the performance criteria in confirmatory analysis for veterinary drug residue analysis using mass spectrometric detection in selected reaction monitoring mode
    Berendsen, Bjorn J.A. ; Meijer, Thijs ; Wegh, Robin ; Mol, Hans G.J. ; Smyth, Wesley G. ; Armstrong Hewitt, S. ; Ginkel, Leen van; Nielen, Michel W.F. - \ 2016
    Drug Testing and Analysis 8 (2016)5-6. - ISSN 1942-7603 - p. 477 - 490.
    confirmatory analysis - ion ratio - liquid chromatography - mass spectrometry - performance criteria

    Besides the identification point system to assure adequate set-up of instrumentation, European Commission Decision 2002/657/EC includes performance criteria regarding relative ion abundances in mass spectrometry and chromatographic retention time. In confirmatory analysis, the relative abundance of two product ions, acquired in selected reaction monitoring mode, the ion ratio should be within certain ranges for confirmation of the identity of a substance. The acceptable tolerance of the ion ratio varies with the relative abundance of the two product ions and for retention time, CD 2002/657/EC allows a tolerance of 5%. Because of rapid technical advances in analytical instruments and new approaches applied in the field of contaminant testing in food products (multi-compound and multi-class methods) a critical assessment of these criteria is justified. In this study a large number of representative, though challenging sample extracts were prepared, including muscle, urine, milk and liver, spiked with 100 registered and banned veterinary drugs at levels ranging from 0.5 to 100 µg/kg. These extracts were analysed using SRM mode using different chromatographic conditions and mass spectrometers from different vendors. In the initial study, robust data was collected using four different instrumental set-ups. Based on a unique and highly relevant data set, consisting of over 39 000 data points, the ion ratio and retention time criteria for applicability in confirmatory analysis were assessed. The outcomes were verified based on a collaborative trial including laboratories from all over the world. It was concluded that the ion ratio deviation is not related to the value of the ion ratio, but rather to the intensity of the lowest product ion. Therefore a fixed ion ratio deviation tolerance of 50% (relative) is proposed, which also is applicable for compounds present at sub-ppb levels or having poor ionisation efficiency. Furthermore, it was observed that retention time shifts, when using gradient elution, as is common practice nowadays, are mainly observed for early eluting compounds. Therefore a maximum retention time deviation of 0.2 min (absolute) is proposed. These findings should serve as input for discussions on the revision of currently applied criteria and the establishment of a new, globally accepted, criterion document for confirmatory analysis.

    In Vitro Fermentation of Porcine Milk Oligosaccharides and Galacto-oligosaccharides Using Piglet Fecal Inoculum
    Difilippo, Elisabetta ; Pan, Feipeng ; Logtenberg, Madelon ; Willems, Rianne ; Braber, Saskia ; Fink-Gremmels, Johanna ; Schols, Henk A. ; Gruppen, Harry - \ 2016
    Journal of Agricultural and Food Chemistry 64 (2016)10. - ISSN 0021-8561 - p. 2127 - 2133.
    fibers - gas chromatography - human fermentation - liquid chromatography - nondigestible carbohydrates - organic acids - short-chain fatty acids - sugars

    In this study, the in vitro fermentation by piglet fecal inoculum of galacto-oligosaccharides (GOS) and porcine milk oligosaccharides (PMOs) was investigated to identify possible preferences for individual oligosaccharide structures by piglet microbiota. First, acidic PMOs and GOS with degrees of polymerization 4-7 were depleted within 12 h of fermentation, whereas fucosylated and phosphorylated PMOs were partially resistant to fermentation. GOS structures containing β1-3 and β1-2 linkages were preferably fermented over GOS containing β1-4 and β1-6 linkages. Upon in vitro fermentation, acetate and butyrate were produced as the main organic acids. GOS fermentation by piglet inoculum showed a unique fermentation pattern with respect to preference of GOS size and organic acids production.

    Oligosaccharides in Urine, Blood, and Feces of Piglets Fed Milk Replacer Containing Galacto-oligosaccharides
    Difilippo, Elisabetta ; Bettonvil, Monique ; Willems, Rianne ; Braber, Saskia ; Fink-Gremmels, Johanna ; Jeurink, Prescilla V. ; Schoterman, Margriet H.C. ; Gruppen, Harry ; Schols, Henk A. - \ 2015
    Journal of Agricultural and Food Chemistry 63 (2015)50. - ISSN 0021-8561 - p. 10862 - 10872.
    absorption - capillary electrophoresis - creatinine - fermentation - GOS - intestine - liquid chromatography - mass spectrometry - pig - prebiotics

    Human milk oligosaccharides (HMOs) are absorbed into the blood (about 1% of the HMO intake) and subsequently excreted in urine, where they may protect the infant from pathogen infection. As dietary galacto-oligosaccharides (GOS) have partial structural similarities with HMOs, this study investigated the presence of GOS and oligosaccharides originating from milk replacer in blood serum, urine, and cecal and fecal samples of piglets, as a model for human infants. Using liquid chromatography-mass spectrometry and capillary electrophoresis with fluorescence detection, oligosaccharides originating from piglet diet including 3′-sialyllactose and specific GOS ranging from degree of polymerization 3 to 6 were detected in blood serum and in urine of piglets. In blood serum, GOS levels ranged from 16 to 23 μg/mL, representing about 0.1% of the GOS daily intake. In urine, approximately 0.85 g of GOS/g of creatinine was found. Cecum digesta and feces contained low amounts of oligosaccharides, suggesting an extensive GOS intestinal fermentation in piglets.

    New applications of the interaction between diols and boronic acids
    Duval, F.L. - \ 2015
    Wageningen University. Promotor(en): Han Zuilhof, co-promotor(en): Teris van Beek. - Wageningen : Wageningen University - ISBN 9789462574717 - 131
    antilichamen - immobilisatie - boorzuur - biomarkers - vloeistofchromatografie - antibodies - immobilization - boric acid - biomarkers - liquid chromatography

    Florine Duval - New applications of the interaction between diols and boronic acids – Summary

    Chapter 1 introduces the theory and known applications of the interaction between boronic acids and diols, and explains the context of this thesis. Diagnosis of depression was the initial goal of this multidisciplinary project. The focus of the PhD project was the development of a strategy to immobilize antibodies on the surface of a chip in such a way that very low concentrations (~ 1 pM) of biomarkers for depression could be detected in urine. To achieve this, the immobilization of antibodies using boronic acids seemed promising.

    However, preliminary experiments and further insights revealed the many challenges that this immobilization strategy faces, giving rise to Chapter 2. This chapter discusses several important points that need to be taken into account when one plans to immobilize antibodies via boronic acids: choice of the boronic acid structure and spacer to attach it to the surface, use of an antifouling polymer, choice of an antibody with suitable glycosylation, optimization of the conditions for antibody immobilization...

    One big issue for antibody immobilization using boronic acids is the reversibility of the reaction between boronic acids and diols, hence the possible release of the antibody from the surface.

    Chapter 3 describes the design and synthesis of boronic acid-containing linkers that would enable the oriented and irreversible immobilization of antibodies. Two linkers were designed with an amine for surface attachment, a boronic acid for capturing antibodies via the N-glycans in their Fc chain, and a diazirine for irreversible immobilization upon UV irradiation while maintaining antibody orientation. From a diazirine building-block that was obtained in three steps, the first linker was synthesized in four steps and the second linker was synthesized in three steps. Diol-functionalized silica was used for the chromatography of two boronic acid-containing intermediates, this method being novel (to the best of our knowledge) and likely based on boronic acid-diol interactions. High-resolution mass spectrometry, through matching exact masses, matching isotope patterns and observation of species corresponding to the esterification of boronic acids with MeOH, confirmed that both linkers were synthesized successfully.

    During the synthesis of boronic acid-containing linkers, it was difficult to see which spots on TLC plates corresponded to boronic acids. To solve this problem, a new TLC staining method based on the reaction between boronic acids and alizarin was developed.

    Chapter 4 presents this work in detail. After optimization experiments, 1 mM alizarin in acetone was shown to be the preferred staining solution. When the TLC plate was briefly dipped in this solution, allowed to dry in ambient air and observed under 365 nm light, bright yellow fluorescent spots were observed where boronic acids were present. Phenylboronic acid was detected at a concentration as low as 0.1 mM. A range of boronic acids and derivatives was successfully detected, and boron-free compounds resulted in no or very weak fluorescence. The staining method was further tested in the monitoring of three reactions involving boronic acids, and provided clear information about the consumption or formation of boronic acid-containing compounds.

    Although TLC is useful to synthetic chemists, analysis of reaction mixtures by HPLC is sometimes necessary for obtaining more accurate information or for optimization of preparative HPLC conditions.

    Chapter 5 presents the development and applicability of a method for the on-line HPLC detection of boronic acids using alizarin. After optimization experiments at an HPLC flow rate of 0.40 mL/min, the HPLC-separated analytes were mixed post-column with a solution of 75 μM alizarin and 0.1% triethylamine in ACN, which was delivered at a flow rate of 0.60 mL/min. The reaction between alizarin and boronic acids occurred in a reaction coil of dimensions of 3.5 m × 0.25 mm at a temperature of 50 °C, resulting in fluorescent complexes that were detected as positive peaks by a fluorescence detector (lexc 469 nm and lem 610 nm). The method enabled the selective detection of various boronic acids and derivatives, with a limit of detection of phenylboronic acid of 1.2 ng or 1 μM. It could successfully monitor the progress of two organic reactions involving boronic acid-containing compounds, and provided useful insights into the course of the reactions.

    Chapter 6 provides a reflexion about the work presented in this thesis, suggestions for future research, and a general conclusion.

    Challenging the claims on the potential of biochar to mitigate climate change
    Francischinelli Rittl, T. - \ 2015
    Wageningen University. Promotor(en): Thomas Kuijper; Ellis Hoffland; Bas Arts, co-promotor(en): E.H. Novotny. - Wageningen : Wageningen University - ISBN 9789462573253 - 145
    klimaatverandering - mitigatie - biochar - bodem - organische koolstof - vloeistofchromatografie - koolstofvastlegging in de bodem - brazilië - climatic change - mitigation - biochar - soil - organic carbon - liquid chromatography - soil carbon sequestration - brazil

    Summary

    In this PhD thesis I studied the influence of biochar discourses on the political practices in Brazil and the impact of biochar on soil organic carbon (SOC) stocks, thus contributing to the current debate on the potential of biochar to mitigate climate change. Biochar is the solid material obtained from the carbonization of biomass. The deliberate production and application to soil distinguishes biochar from other carbonized products, e.g. charcoal. Inspired by the aged charcoal found in the fertile Amazonian Dark Earth (ADE; also known as Terra Preta de Índio), the current application of biochar in soil is claimed to simultaneously address four global challenges: food production, climate change, energy supply and waste reduction (Chapter 1). Biochar is supposed to be an absorbent and stable material, which can be used to retain nutrients in the soil, increasing agricultural productivity, while sequestering carbon over extended periods of time. Therefore, biochar is claimed to be a means to mitigate global climate change. Furthermore, if biochar is produced in a modern pyrolysis plant, it also can co-produce bio-oil and syngas that could be used as energy. And if biochar is produced by carbonization of agricultural residue, biochar may reduce the quantity of solid waste that needs to be disposed of.

    In Chapter 2, I analysed the policy arrangement related to biochar along the four dimensions of the policy arrangement approach, which are actors, discourse, power and rules. I focused on Brazil, which is an important player in the international biochar debate. My analysis shows that scientists in research institutions are the dominant players in the network, while policymakers, businessmen and farmers are marginally positioned. Experts from Embrapa occupy central positions and thus exercise most power in the network. Moreover, experts linked to ADE have lost prominence in the network. The cause for this reduction was the shift from the ADE/biochar to the biochar/technology discourse. The latter discourse includes different coalitions, such as: ‘climate change mitigation’, ‘improvement of soil fertility’ and ‘improving crop residue management’. Although the biochar/climate coalition is dominant at international level, it is far less prominent in Brazil. Nationally the discourses of ‘improvement of soil fertility’ and ‘improving crop residue management’ have particularly prompted actors’ relationships and practices. However, the biochar/technology discourse is not (yet) institutionalized into formal rules in Brazil.

    As a consequence, the country lacks an established biochar policy field. Brazilian biochar practices focus on the carbonization of the available residues into biochar and on the application of biochar in soils to increase the SOC content and consequently the fertility of these soils. In this context, in Chapter 3 I tested in the field the potential of biochar produced in traditional kilns to increase the C contents of sandy savannah soils. My results show that biochar produced in traditional kilns is less thermally altered than that produced by industrial kilns and therefore rapidly decomposes. The decomposition rate of traditionally produced biochar was higher (decomposition constant k = 0.32-1.00 year-1) than generally assumed (k = 0.0005-0.005 year-1), and higher than the decomposition of native SOC (k = 0.22 year-1). In Chapter 4 I demonstrated in a short-term laboratory experiment that oilseed-derived biochar had a similar or higher decomposition rate than native SOC. My results show that all three tested oilseed biochars decelerate the decomposition of SOC in the biochar-amended soils, with biochar richer in aromatics having a stronger negative effect than biochar richer in aliphatics. Therefore, oilseed biochar directly increases soil C stocks and indirectly raises soil C sequestration in the short term through decreasing the decomposition of native SOC.

    In my research, the decomposition studies were performed using 13C isotope analysis. However, the 13C isotope analysis cannot be used when the differences of 13C isotope abundance between biochar and soil are not sufficiently large. Therefore, its use can be limited. In Chapter 5, I aimed at improving the benzene polycarboxylic acid (BPCA) method. I re-designed the protocols of the BPCA method and found a better and faster way to quantify and characterize the BPCAs derived from biochar, compared to the previous protocols. The improved method was then successfully tested and implemented in a laboratory in Brazil.

    Combining my findings with results of the literature, I conclude (Chapter 6) that there is no evidence that biochar is a reliable way for C sequestration in sandy soils under savannah environments. Biochar decomposition is highly variable, depending on charring conditions, soil and climate: (i) biochar produced by traditional kilns is less thermally degraded than those pyrolysed by industrial kilns; (ii) in sandy soils less biochar accumulates than in clay-silt soils; and (iii) warm-dry conditions raise the decomposition of biochar. These conclusions have a direct consequence for the development of policies on biochar, because we cannot ensure that biochar will sequester the same quantity of C for the same period at different geographical regions.

    Authentication of organic eggs by LC fingerprinting and isotope ratio analysis
    Ruth, S.M. van; Rogers, K. ; Newton-Smith, E. ; Koot, A.H. ; Alewijn, M. - \ 2012
    analytische methoden - massaspectrometrie - vloeistofchromatografie - eieren - biologische voedingsmiddelen - principale componentenanalyse - analytical methods - mass spectrometry - liquid chromatography - eggs - organic foods - principal component analysis
    The aim of the present study was to develop and modify fingerprint methodology for the verification of Dutch organic eggs versus conventional (barn/free range) eggs.
    Identification of unknown residues : using bioassay directed fractionation, UPLC/TOFMS analysis and database searching
    Peters, R.J.B. ; Rijk, J.C.W. ; Oosterink, J.E. ; Nijrolder, A.W.J.M. ; Nielen, M.W.F. - \ 2009
    Wageningen : Rikilt - Institute of Food Safety (Report / RIKILT 2009.013) - 47
    residuen - analytische methoden - biotesten - vloeistofchromatografie - massaspectrometrie - residues - analytical methods - bioassays - liquid chromatography - mass spectrometry
    Nowadays a large number of compounds are determined in environmental and food samples. Biological tests are used to screen samples for large groups of compounds having a particular effect, but it is often difficult to identify a specific compound when a positive effect is observed. The identification of an unknown compound is a challenge for analytical chemistry in environmental analysis, food analysis, as well as in clinical and forensic toxicology. This study reports on the development of a procedure for the identification of unknown residues in samples suspected of containing illegal substances and samples showing bioactivity in bioassay - or microbiological screening assays. For testing purposes several samples were selected; a number of so-called "cold cases", historical samples that were suspected of containing illegal growth promoting substances, herbal mixtures and sport supplements.
    Biosensing Bioactive Contaminants, Assay Development and Hyphenation with Mass Spectrometry
    Marchesini, G.R. - \ 2008
    VU University Amsterdam. Promotor(en): H. Irth; Michel Nielen, co-promotor(en): E.P. Meulenberg. - Wageningen : RIKILT - 230
    biosensoren - besmetters - analytische methoden - vloeistofchromatografie - massaspectrometrie - bioactieve verbindingen - biosensors - contaminants - analytical methods - liquid chromatography - mass spectrometry - bioactive compounds
    Ontwikkeling van een LC-MSMS methode voor de kwalitatieve en kwantitatieve bepaling van cyclopiazonzuur in diervoeder en tarwemeel
    Rijk, T.C. de; Zomer, P. ; Moorhof, S. ; Traag, W.A. - \ 2006
    Wageningen : RIKILT (Rapport / RIKILT 2006.004)
    cyclopiazonzuur - voer - tarwebloem - vloeistofchromatografie - analytische methoden - cyclopiazonic acid - feeds - wheat flour - liquid chromatography - analytical methods
    Ontwikkeling en implementatie van een LC-MS bevestigingsmethode voor de bepaling van mycotoxinen in diervoeders en diervoedergrondstoffen
    Rijk, T. de; Zomer, P. ; Traag, W.A. - \ 2003
    Wageningen : RIKILT (Report / RIKILT 2003.011) - 11
    mycotoxinen - voer - ruwe grondstoffen - vloeistofchromatografie - massaspectrometrie - mycotoxins - feeds - raw materials - liquid chromatography - mass spectrometry
    Methodeontwikkeling voor de bepaling van polaire bestrijdingsmiddelen met behulp van vloeistofchromatografie-massaspectrometrie (LC-MS) : fase 2 initiërend onderzoek
    Rijk, T.C. de; Zomer, P. ; Traag, W.A. - \ 2002
    Wageningen : Rijks-Kwaliteitsinstituut voor land- en tuinbouwproducten (RIKILT) (Rapport RIKILT 2002.001) - 16
    pesticidenresiduen - vloeistofchromatografie - massaspectrometrie - analytische methoden - pesticide residues - liquid chromatography - mass spectrometry - analytical methods
    Analysis of chlormequat in pear and leaves of pear using liquid chromatography/mass spectrometry
    Rijk, T.C. de; Zomer, P. ; Traag, W.A. - \ 2002
    Wageningen : RIKILT (Rapport RIKILT 2002.003) - 15
    chloormequat - peren - vloeistofchromatografie - massaspectrometrie - chlormequat - pears - liquid chromatography - mass spectrometry
    Methodeontwikkeling voor de bepaling van polaire bestrijdingsmiddelen met behulp van vloeistofchromatografie-masssaspectrometrie (LC-MS) Fase 2 Initiërend onderzoek
    Rijk, T.C. de; Zomer, P. ; Traag, W.A. - \ 2002
    Wageningen : Rijks-Kwaliteitsinstituut voor land- en tuinbouwproducten (RIKILT) (Rapport RIKILT 2002.001) - 16 p.
    pesticide residues - liquid chromatography - mass spectrometry - analytical methods
    Nitroimidazole interlaboratory study 03/01
    Berendsen, B.J.A. ; Rhijn, J.A. van - \ 2001
    Wageningen : RIKILT (Report / RIKILT 2001.023)
    spieren - dimetridazol - ronidazol - metronidazol - hplc - vloeistofchromatografie - massaspectrometrie - metabolieten - kwaliteitscontroles - analytische scheikunde - muscles - dimetridazole - ronidazole - metronidazole - hplc - liquid chromatography - mass spectrometry - metabolites - quality controls - analytical chemistry
    Literatuurstudie ten behoeve van de methodeontwikkeling voor de analyse van residuen van polaire en/of thermisch instabiele bestrijdingsmiddelen in vegetatie, voedingsmiddelen en daaraan gerelateerde matrices op laag niveau
    Blok-Tip, L. - \ 2001
    Wageningen : RIKILT (Rapport / RIKILT 2001.013) - 30
    pesticidenresiduen - hplc - vloeistofchromatografie - massaspectrometrie - literatuuroverzichten - analytische scheikunde - pesticide residues - hplc - liquid chromatography - mass spectrometry - literature reviews - analytical chemistry
    Proficiency study for the analysis of chloramphenicol in porcine muscle
    Berendsen, B.J.A. ; Lasaroms, J.J.P. ; Rhijn, J.A. van - \ 2001
    Wageningen : RIKILT (Report / RIKILT 2001.024) - 11
    chlooramfenicol - vloeistofchromatografie - massaspectrometrie - varkensvlees - nederland - chloramphenicol - liquid chromatography - mass spectrometry - pigmeat - netherlands
    Proficiency study for the analysis of chloramphenicol in procine muscle
    Berendsen, B.J.A. ; Lasaroms, J.J.P. ; Rhijn, J.A. van - \ 2001
    Wageningen : State Institute for Quality Control of Agricultural Products (RIKILT) (Rapport RIKILT 2001.024) - 11 p.
    chloramphenicol - liquid chromatography - mass spectrometry - pigmeat
    Ontwikkeling van een vloeistofchromatografische methode voor de bepaling van residuen van meticlorpindol in pluimveevlees
    Beek, W.M.J. ; Keukens, H.J. - \ 1994
    Wageningen : DLO-Rijks-Kwaliteitsinstituut voor Land- en Tuinbouwprodukten (Rapport / RIKILT-DLO 94.34) - 14
    vloeistofchromatografie - hplc - pluimveevlees - kippenvlees - eendenvlees - coccidiose - theileria - liquid chromatography - hplc - poultry meat - chicken meat - duck meat - coccidiosis - theileria
    In dit rapport wordt de ontwikkeling van een methode beschreven voor de bepaling van residuen van meticlorpindol in pluimveevlees met behulp van HPLC en UV-detectie. Er is onderzoek verricht naar de chromatografische scheiding van meticlorpindol op reversed phase kolommen, naar een geschikte extractiemethode en de zuivering en concentratie van de extracten.
    LC-MS analyse van [beta] - caroteen en retinol
    Rhijn, J.A. van; Heskamp, H.H. ; Lieshout, M. van - \ 1994
    Wageningen : DLO-Rijks-Kwaliteitsinstituut voor Land- en Tuinbouwprodukten (Rapport / RIKILT-DLO 94.28) - 12
    retinol - carotenen - metabolisme - vloeistofchromatografie - massaspectrometrie - retinol - carotenes - metabolism - liquid chromatography - mass spectrometry
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