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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Ultra-fast retroactive processing of liquid chromatography high-resolution full-scan Orbitrap mass spectrometry data in anti-doping screening of human urine
Lommen, Arjen ; Elaradi, Abdurzag ; Vonaparti, Ariadni ; Blokland, Marco ; Nielen, Michel W. ; Saad, Khadija Ali ; Abushreeda, Wadha Masoud ; Horvatovich, Peter ; Al-Muraikhi, Amal Essa ; Al-Maadheed, Mohammed ; Georgakopoulos, Costas - \ 2019
Rapid Communications in Mass Spectrometry 33 (2019)20. - ISSN 0951-4198 - p. 1578 - 1588.

Rationale: Retroactive analysis of previously tested urine samples has become an important sports anti-doping tool. Retroactive reprocessing of old data files acquired from a generic screening procedure can reveal detection of initially unknown substances, like illegal drugs and newly identified metabolites. Methods: To be able to efficiently search through hundreds to thousands of liquid chromatography high-resolution full-scan Orbitrap mass spectrometry data files of anti-doping samples, a combination of MetAlign and HR_MS_Search software has been developed. MetAlign reduced the data size ca 100-fold making possible local storage of a massive volume of data. Results: The newly developed HR_MS_Search module can search through the reduced data files for new compounds (mass or isotope pattern) defined by mass windows and retention time windows. A search for 33 analytes in 940 reduced data files lasted 10 s. The output of the automatic search was compared to the standard manual routine evaluation. The results of searching were evaluated in terms of false negatives and false positives. The newly banned b2-agonist higenamine and its metabolite coclaurine were successfully searched in reduced data files originating from a testing period for which these substances were not banned, as an example of retroactive analysis. Conclusions: The freeware MetAlign software and its automatic searching module HR_MS_Search facilitated the retroactive reprocessing of reduced full-scan high-resolution liquid chromatography/mass spectrometry screening data files and created a new tool in anti-doping laboratories' network.

Diffusion of hydrophilic organic micropollutants in granular activated carbon with different pore sizes
Piai, Laura ; Dykstra, Jouke E. ; Adishakti, Mahesa G. ; Blokland, Marco ; Langenhoff, Alette A.M. ; Wal, Albert van der - \ 2019
Water Research 162 (2019). - ISSN 0043-1354 - p. 518 - 527.
Activated carbon - Adsorption kinetics - Hydrophilic micropollutants - Intra-particle diffusion - Pore diffusion

Hydrophilic organic micropollutants are commonly detected in source water used for drinking water production. Effective technologies to remove these micropollutants from water include adsorption onto granular activated carbon in fixed-bed filters. The rate-determining step in adsorption using activated carbon is usually the adsorbate diffusion inside the porous adsorbent. The presence of mesopores can facilitate diffusion, resulting in higher adsorption rates. We used two different types of granular activated carbon, with and without mesopores, to study the adsorption rate of hydrophilic micropollutants. Furthermore, equilibrium studies were performed to determine the affinity of the selected micropollutants for the activated carbons. A pore diffusion model was applied to the kinetic data to obtain pore diffusion coefficients. We observed that the adsorption rate is influenced by the molecular size of the micropollutant as well as the granular activated carbon pore size.

Ambient Ionization for direct food analysis
Blokland, M.H. - \ 2018
Ambient Ionization for direct food analysis
Blokland, Marco - \ 2018
Comparison of gas chromatography/quadrupole time-of-flight and quadrupole Orbitrap mass spectrometry in anti-doping analysis : I. Detection of anabolic-androgenic steroids
Abushareeda, Wadha ; Tienstra, Marc ; Lommen, Arjen ; Blokland, Marco ; Sterk, Saskia ; Kraiem, Suhail ; Horvatovich, Peter ; Nielen, Michel ; Al-Maadheed, Muhammad ; Georgakopoulos, Costas - \ 2018
Rapid Communications in Mass Spectrometry 32 (2018)23. - ISSN 0951-4198 - p. 2055 - 2064.

Rationale: The World Anti-Doping Agency (WADA) encourages drug-testing laboratories to develop screening methods that can detect as many doping substances as possible in urine. The use of full-scan high-resolution acquisition (FS/HR) with gas chromatography/mass spectrometry (GC/MS) for the detection of known and unknown trimethylsilyl (TMS) derivatives of anabolic-androgenic steroids (AAS) provides anti-doping testing bodies with a new analytical tool. Methods: The AAS were extracted from urine samples by generic liquid–liquid extraction, after enzymatic hydrolysis, and TMS derivatization. The extracted urine was analyzed by GC/Q-TOF and GC/Q-Orbitrap to compare the performance of the two instrument types for the detection of 46 AAS in human urine. The quantitation of endogenous anabolic steroids and the ability of the two analytical platforms to comply with the requirements for testing as part of the WADA Athlete Biological Passport (ABP) were also assessed. Results: The data presented show that the analytical performance for both instruments complies with the WADA specifications. The limits of detection (LODs) for both instruments are well below the WADA 50% Minimum Required Performance Levels. The mass errors in the current study for the GC/Q-Orbitrap platform are lower than those obtained for the GC/Q-TOF instrument. Conclusions: The data presented herein proved that both molecular profiling platforms can be used for antidoping screening. The mass accuracies are excellent in both instruments; however, the GC/Q-Orbitrap performs better as it provides higher resolution than the GC/Q-TOF platform.

Multiclass screening in urine by comprehensive two-dimensional liquid chromatography time of flight mass spectrometry for residues of sulphonamides, beta-agonists and steroids
Blokland, M.H. ; Zoontjes, P.W. ; Ginkel, L.A. van; Schans, M.G.M. van de; Sterk, S.S. ; Bovee, T.F.H. - \ 2018
Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 35 (2018)9. - ISSN 1944-0049 - p. 1703 - 1715.
Antibiotics - comprehensive 2D-LC - growth promoters - LC x LC - mass spectrometry - residues

Nowadays routine residue monitoring involves the analysis of many compounds from different classes, mainly in urine. In the past two decades, developments heavily focused on the use of mass spectrometers (MS) and faster and more sensitive MS detectors have reached the market. However, chromatographic separation (CS) was rather ignored and the cognate developments in CS were not in line. As a result, residue analysis did not improve to the extent anticipated. CS by LC x LC is a promising technique and will enable a further increase in the range of compounds and compound classes that can be detected in a single run. In the present study, a self-built LC x LC system, using a 10 port valve, was connected to a single quadrupole MS with electrospray interface. Standards containing a mixture of sulphonamides, β-agonists and (steroid) hormones, 53 compounds, in total, were analysed. Results demonstrated that these compounds were well separated and could be detected at low levels in urine, i.e. limit of detection (LOD) from 1 µg L−1 for most β-agonists to 10 µg L−1 for some sulphonamides and most hormones. To enhance the sensitivity, optimisation was performed on an advanced commercial LC x LC system connected to a full scan accurate MS. This ultimately resulted in a fast high throughput untargeted method, including a simple sample clean-up in a 96-well format, for the analysis of urine samples.

Diergeneesmiddelen & hormonen in het milieu door de toediening van drijfmest : Een verkennende studie in de Provincie Gelderland naar antibiotica, antiparasitaire middelen, coccidiostatica en natuurlijke hormonen in mest, (water)bodem, grondwater en oppervlaktewater
Lahr, Joost ; Derksen, Anja ; Wipfler, Louise ; Schans, Milou van de; Berendsen, Bjorn ; Blokland, Marco ; Dimmers, Wim ; Bolhuis, Popko ; Smidt, Rob - \ 2018
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2898) - 89
Het voorkomen, de risico’s en de mogelijkheden voor emissiereductie van humane geneesmiddelen in water krijgen de afgelopen jaren steeds meer aandacht. Naar diergeneesmiddelen gaat tot op heden minder aandacht uit dan naar humane geneesmiddelen. In 2017 is daarom onderzoek verricht naar de lotgevallen van diergeneesmiddelen in drijfmest uit de intensieve veehouderij die toegediend wordt op het land. Het onderzoek richtte zich op de kalver- en varkenshouderij en met name op het risico van uitspoeling. Voor het onderzoek werden vijf op zandgrond gelegen bedrijven in Gelderland geselecteerd uit iedere sector. Voorafgaand aan de mesttoediening werd een monster van de mest zelf genomen en op diverse tijdstippen voor en na de mestinjectie werden de bodem, het grondwater en het oppervlaktewater en sediment van kavelsloten naast de bemeste percelen bemonsterd. In al deze monsters werden de concentraties van een groot aantal antibiotica, antiparasitaire middelen, coccidiostatica en natuurlijke hormonen bepaald middels chemische analyse.
Evaluation of attenuation of pharmaceuticals, toxic potency, and antibiotic resistance genes in constructed wetlands treating wastewater effluents
He, Yujie ; Nurul, Sabri ; Schmitt, Heike ; Sutton, Nora B. ; Murk, Tinka A.J. ; Blokland, Marco H. ; Rijnaarts, Huub H.M. ; Langenhoff, Alette A.M. - \ 2018
Science of the Total Environment 631-632 (2018). - ISSN 0048-9697 - p. 1572 - 1581.
ARGs - Bioanalyses - Domestic wastewater - Micropollutants - Multivariate analysis - Tertiary treatment
The performance of constructed wetlands (CWs) in the removal of pharmaceutically active compounds (PhACs) is generally evaluated on the basis of chemical analysis. In this work, we used a combination of chemical, toxicological, and molecular analyses to assess the attenuation of PhACs, toxic potency and antibiotic resistance genes (ARGs) in a field study of three CWs serving as tertiary treatment of wastewater treatment plants. First, 17 PhACs were analysed chemically, of which 14 were detected and seven at concentrations >0.1 μg/l. Even though some of the individual PhACs were moderately or highly removed in the CWs investigated, median removal of overall PhACs was approximately 50% in the vertical subsurface flow CW (VSF-CW) with a lower hydraulic loading rate while the removal in the other two free water surface flow CWs (SF-CWs) was negligible. Second, toxic potency of wastewater extracts was assessed in a range of bioassays. Estrogenicity was overall attenuated in CWs, while the neurotoxic potency of wastewater extracts did not decrease after passage through the two CWs investigated. Third, the VSF-CW and one of the SF-CW showed a positive removal of an integrase gene and three ARGs tested. The increased concentrations of ARGs in the other SF-CW, as well as the increase of total bacteria in all CWs, may relate to regrowth of resistance-carrying bacteria. Finally, multivariate analysis shows that most PhACs are positively correlated to the observed toxic potency. Additionally, low removal of organics and nutrients seems to parallel with low removal of PhACs. ARGs positively correlated with organics, nutrients and some PhACs, and the integrase gene but not to the respective antibiotics. The insufficient removal of PhACs, toxic potency, and ARGs indicates the need of an optimal design of CWs as tertiary treatment facilities.
Enhancing detectability of anabolic-steroid residues in bovine urine by actively modulated online comprehensive two-dimensional liquid chromatography - high-resolution mass spectrometry
Baglai, Anna ; Blokland, Marco H. ; Mol, Hans G.J. ; Gargano, Andrea F.G. ; Wal, Sjoerd van der; Schoenmakers, Peter J. - \ 2018
Analytica Chimica Acta 1013 (2018). - ISSN 0003-2670 - p. 87 - 97.
Active modulation - Anabolic steroids - Comprehensive two-dimensional liquid chromatography - LC×LC - Residue analysis - Signal enhancement
In this study we describe an approach to enhance the sensitivity of an online comprehensive two-dimensional liquid chromatography (LC × LC) high-resolution mass spectrometry method for the separation and detection of trace levels of anabolic-steroid residues in complex urine matrices.Compared to one-dimensional liquid chromatography (1D-LC), LC × LC methods offer higher separation power, thanks to the combined effect of two different selectivities and a higher peak capacity. However, when using state-of-the-art LC × LC instrumentation, the price paid for the increase in separation power is a decrease in sensitivity and detectability of trace-level analytes. This can be ascribed to the sample dilution that takes place during each of the two chromatographic steps. The way in which fractions are collected and transferred from the first to the second column is also of paramount importance, especially the volume and the solvent composition of the fractions injected in the second column.To overcome the detection limitation, we present an active-modulation strategy, based on concentrating the fractions of the first-dimension effluent using a modulation interface that employs trap columns. We obtained a signal enhancement for anabolic-steroid compounds in a bovine-urine sample by a factor of 2.4-7.6 and an increase in the signal-to-noise ratio up to a factor of 7 in comparison with a standard loop-based modulation interface. In addition, thanks to the increased sensitivity of our method, a substantially larger number of peaks were detected (76 vs. 36). Moreover, we could reduce the solvent consumption by a factor of three (160 mL vs. 500 mL per run).
A Fast Quantitative Multi-analyte Method for Growth Promoters in Bovine Meat Using Bead-Disruption, 96-well SPE Clean-up and Narrow-Bore UHPLC-MS/MS Analysis
Tricht, Frederike van; Essers, Martien ; Groot, Maria ; Sterk, Saskia ; Blokland, Marco ; Ginkel, Leen van - \ 2018
Food Analytical Methods 11 (2018)8. - ISSN 1936-9751 - p. 2206 - 2217.
96-wells SPE - Bead-disruption - Bovine meat - Growth promoters - Multi-analyte analysis - UHPLC-MS/MS
A new method for detecting low levels of growth promoters in bovine meat was developed with the following goal: easy, fast and sensitive analysis of a wide range of compounds, with reduced consumption of chemicals and disposables. Several classes of growth promoters were included, i.e. resorcylic acid lactones (RALs) and steroids, the latter including corticosteroids and gestagens. For sample treatment, 0.5 g of homogenised bovine meat was simultaneously disrupted and extracted in a bead-ruptor machine. The organic extraction solvent was further processed by solid-phase extraction (SPE) clean-up using 96-Well Oasis® HLB Plates. Six SPE washing steps were applied to remove matrix compounds after which the growth promoters were eluted and analysed using UHPLC-MS/MS. To achieve lower detection levels and to reduce LC-solvent consumption, a narrow-bore column with an internal diameter of 1 mm was used, instead of the conventional 2.1 mm. During analysis, the mass spectrometer was operated in negative and positive ionisation mode (ion switching). The newly developed method was validated according to the Commission Decision 2002/657. The results demonstrate that the method meets the criteria as established in this Commission Decision. The precision of the method for exogenous steroids varies between 85 and 115%, the CCα for the compounds ranges from 0.1–0.9 μg kg−1 and the expanded measurement uncertainty was lower than 36%. Compared to our current in-house methods with analysis times of 2 days for a maximum of 24 samples, the new method offers improved sample throughput (96 samples in less than 24 h) and lower detection limits.
Methods and means for determining treatment of subjects with exogenous somatotropin
Smits, N.G.E. ; Blokland, M.H. ; Nielen, M.W.F. - \ 2017
Octrooinummer: US2017354717, verleend: 2017-12-14.
Described are methods for determining whether a subject has been treated with exogenous somatotropin. The disclosure further relates to kits for determining whether a subject has been treated with exogenous somatotropin, and to the use of such kits for determining whether a subject has been treated with exogenous somatotropin.
Applicability of an innovative steroid-profiling method to determine synthetic growth promoter abuse in cattle
Blokland, M.H. ; Tricht, E.F. van; Ginkel, L.A. van; Sterk, S.S. - \ 2017
Journal of Steroid Biochemistry and Molecular Biology 174 (2017). - ISSN 0960-0760 - p. 265 - 275.
A robust LC–MS/MS method was developed to quantify a large number of phase I and phase II steroids in urine. The decision limit is for most compounds lower than 1 ng ml−1 with a measurement uncertainty smaller than 30%. The method is fully validated and was applied to assess the influence of administered synthetic steroids and beta-agonists on the steroidogenesis. From three animal experiments, clenbuterol, diethylstilbestrol and stanozolol, the steroid profiles in urine of bovine animals were compared before and after treatment. It was demonstrated that the steroid profiles were altered due to these treatments. A predictive multivariate model was built to identify deviations from normal population steroid profiles. The abuse of synthetic steroids can be detected in urine samples from bovine animals using this model. The samples from the animal experiments were randomly analysed using this method and predictive model. It was shown that these samples were predicted correctly in the exogenous steroids group.
Metabolism of Ibuprofen by Phragmites australis : Uptake and Phytodegradation
He, Yujie ; Langenhoff, Alette A.M. ; Sutton, Nora B. ; Rijnaarts, Huub H.M. ; Blokland, Marco H. ; Chen, Feiran ; Huber, Christian ; Schröder, Peter - \ 2017
Environmental Science and Technology 51 (2017)8. - ISSN 0013-936X - p. 4576 - 4584.

This study explores ibuprofen (IBP) uptake and transformation in the wetland plant species Phragmites australis and the underlying mechanisms. We grew P. australis in perlite under greenhouse conditions and treated plants with 60 μg/L of IBP. Roots and rhizomes (RR), stems and leaves (SL), and liquid samples were collected during 21 days of exposure. Results show that P. australis can take up, translocate, and degrade IBP. IBP was completely removed from the liquid medium after 21 days with a half-life of 2.1 days. IBP accumulated in RR and was partly translocated to SL. Meanwhile, four intermediates were detected in the plant tissues: hydroxy-IBP, 1,2-dihydroxy-IBP, carboxy-IBP and glucopyranosyloxy-hydroxy-IBP. Cytochrome P450 monooxygenase was involved in the production of the two hydroxy intermediates. We hypothesize that transformation of IBP was first catalyzed by P450, and then by glycosyltransferase, followed by further storage or metabolism in vacuoles or cell walls. No significant phytotoxicity was observed based on relative growth of plants and stress enzyme activities. In conclusion, we demonstrated for the first time that P. australis degrades IBP from water and is therefore a suitable species for application in constructed wetlands to clean wastewater effluents containing IBP and possibly also other micropollutants.

Multiple heart-cutting two dimensional liquid chromatography quadrupole time-of-flight mass spectrometry of pyrrolizidine alkaloids
Schans, Milou G.M. van de; Blokland, Marco H. ; Zoontjes, Paul W. ; Mulder, Patrick P.J. ; Nielen, Michel W.F. - \ 2017
Journal of Chromatography. A, Including electrophoresis and other separation methods 1503 (2017). - ISSN 0021-9673 - p. 38 - 48.
Isomeric pyrrolizidine alkaloids - Mass spectrometry - Multiple heart-cutting 2D-LC - Two dimensional liquid chromatography

Pyrrolizidine alkaloids (PAs) and their and the corresponding N-oxides (PAs-ox) are genotoxic plant metabolites which can be present as unwanted contaminants in food products of herbal origin like tea and food supplements. PAs and PAs-ox come in a wide variety of molecular structures including many structural isomers. For toxicity assessment it is important to determine the composition of a sample and to resolve all isomeric PAs and PAs-ox, which is currently not possible in one liquid or gas chromatographic (LC or GC) run. In this study an online two dimensional liquid chromatography quadrupole time-of-flight mass spectrometry (2D-LC QToF-MS) method was developed to resolve isomeric PAs and PAs-ox. After comprehensive column and mobile phase selection a polar endcapped C18 column was used at pH 3 in the first dimension, and a cross-linked C18 column at pH 10 in the second dimension. Injection solvents, column IDs, flow rates and temperatures were carefully optimized. The method with column selection valve switching described in this study was able to resolve and visualize 20 individual PAs/PAs-ox (6 sets of isomers) in one 2D-LC QToF-MS run. Moreover, it was shown that all isomeric PAs/PAs-ox could be unambiguously annotated. The method was shown to be applicable for the determination and quantification of isomeric PAs/PAs-ox in plant extracts and could be easily extended to include other PAs and PAs-ox.

Distinction of clenbuterol intake from drug or contaminated food of animal origin in a controlled administration trial – the potential of enantiomeric separation for doping control analysis
Parr, Maria Kristina ; Blokland, Marco H. ; Liebetrau, Franz ; Schmidt, Alexander H. ; Meijer, Thijs ; Stanic, Mijo ; Kwiatkowska, Dorota ; Waraksa, Emilia ; Sterk, Saskia S. - \ 2017
Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 34 (2017)4. - ISSN 1944-0049 - p. 525 - 535.
The differentiation of clenbuterol abuse and unintentional ingestion from contaminated meat is crucial with respect to the valuation of an adverse analytical finding in human sports doping control. The proportion of the two enantiomers of clenbuterol may serve as potential discriminating parameter. For the determination of the individual enantiomers, specific methods were developed and validated for the different matrices under investigation based on chiral chromatography coupled to tandem mass spectrometry. Data are presented from the administration to humans of clenbuterol from a pharmaceutical preparation, and from cattle meat and liver containing residues. A shift in the proportion of the enantiomers in cattle meat is detected and
this signature is also found in human urine after ingestion. Thus, an altered enantiomeric composition of clenbuterol may be used to substantiate athletes’ claims following adverse analytical findings in doping control. However, in meat, the enantiomeric composition was found to be highly variable. Species as well as tissue dependent variances need to be considered in interpreting enantiomer discrimination. Analysis of post administration urines from a controlled
experiment comparing the administration of racemic clenbuterol from a registered pharmaceutical preparation and the administration of residue-containing meat and liver (nonracemic mixture) from treated animals is reported. Furthermore doping control samples from Mexican U17 World Championship 2011 of the Fédération Internationale de Football Association (FIFA), with adverse analytical findings for clenbuterol, were re-analysed.
Hormones and β-Agonists
Ginkel, L.A. van; Bovee, T.F.H. ; Blokland, M.H. ; Sterk, S.S. ; Smits, N.G.E. ; Pleadin, Jelka ; Vulić, Ana - \ 2016
In: Chemical Analysis of Non-antimicrobial Veterinary Drug Residues in Food / Kay, Jack F., MacNeil, James D., Wang, Jian, Wiley - ISBN 9781118695074
This chapter provides some updated information on contemporary methods for hormone and β-agonist analyses. It deals with the classical approaches for the effective detection and identification of exogenous hormones. The chapter examines specific problems related to control strategies for natural hormones. These include both the traditional and generally recognized natural hormones as well as a series of androgenic steroids that can be present in biological samples obtained from a series of species. The fact that natural background concentrations can be present strongly complicates the analyses. The application of mass spectrometry (MS) in combination with gas chromatography (GC) or liquid chromatography (LC) is considered the "gold standard" for analytical methods in residue analysis. The chapter presents an overview of the available bio-based screening methods for the detection of hormones and ß-agonists, focusing on estrogens, androgens, progestogens, corticosteroids, thyroids, ß2-agonists, and growth hormones (GH).
Sex hormone-binding globulin regulation of androgen bioactivity in vivo : Validation of the free hormone hypothesis
Laurent, Michaël R. ; Hammond, Geoffrey L. ; Blokland, Marco ; Jardí, Ferran ; Antonio, Leen ; Dubois, Vanessa ; Khalil, Rougin ; Sterk, Saskia S. ; Gielen, Evelien ; Decallonne, Brigitte ; Carmeliet, Geert ; Kaufman, Jean Marc ; Fiers, Tom ; Huhtaniemi, Ilpo T. ; Vanderschueren, Dirk ; Claessens, Frank - \ 2016
Scientific Reports 6 (2016). - ISSN 2045-2322

Sex hormone-binding globulin (SHBG) is the high-affinity binding protein for androgens and estrogens. According to the free hormone hypothesis, SHBG modulates the bioactivity of sex steroids by limiting their diffusion into target tissues. Still, the in vivo physiological role of circulating SHBG remains unclear, especially since mice and rats lack circulating SHBG post-natally. To test the free hormone hypothesis in vivo, we examined total and free sex steroid concentrations and bioactivity on target organs in mice expressing a human SHBG transgene. SHBG increased total androgen and estrogen concentrations via hypothalamic-pituitary feedback regulation and prolonged ligand half-life. Despite markedly raised total sex steroid concentrations, free testosterone was unaffected while sex steroid bioactivity on male and female reproductive organs was attenuated. This occurred via a ligand-dependent, genotype-independent mechanism according to in vitro seminal vesicle organ cultures. These results provide compelling support for the determination of free or bioavailable sex steroid concentrations in medicine, and clarify important comparative differences between translational mouse models and human endocrinology.

Characterizing the binding of bovine growth hormone with its induced binding proteins
Smits, N.G.E. ; Blokland, M.H. ; Ginkel, L.A. van; Nielen, M.W.F. - \ 2016
- 1 p.
Long term detectability of recombinant bovine somatotropin in serum and milk
Smits, N.G.E. ; Blokland, M.H. ; Bakhai, Bijol ; Sterk, S.S. ; Nessen, M.A. ; Ginkel, L.A. van; Nielen, M.W.F. - \ 2016
- 1 p.
Protocatechuic acid levels discriminate between organic and conventional wheat from Denmark
Weesepoel, Yannick ; Heenan, Samuel ; Boerrigter-Eenling, Rita ; Venderink, Tjerk ; Blokland, Marco ; Ruth, Saskia Van - \ 2016
Chimia 70 (2016)5. - ISSN 0009-4293 - p. 360 - 363.
Cereals - Food adulteration - Food fraud - Liquid chromatography - Phenolic acids - Wheat

Organic wheat retails at higher market prices than the conventionally grown counterparts. In view of fair competition and sustainable consumer confidence, the organic nature of organic wheat needs to be assured. Amongst other controls this requires analytical tests based on discriminating traits. In this paper, phenolic acids were examined by liquid chromatography analysis as biomarkers for discriminating between the two groups by means of a controlled grown full factorial design Danish wheat sample set. By combining baseline and retention-time correction pre-treatments and principal component analysis, discrimination between organic and conventional produce was found to be expressed in the first principal component (93%), whilst the second principal component accounted for the production year (4%). Upon examination of the loadings plot, a single chromatographic peak was found to account for a large part in the discrimination between the two wheat production systems. This was further underpinned by statistically significant differences found in concentrations between the organic and conventional production systems of this phenolic acid (ANOVA, P

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