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Wageningen, Netherlands

Nielen M.W.F.,RIKILT Wageningen UR | Nielen M.W.F.,Wageningen University | Van Beek T.A.,Wageningen University
Analytical and Bioanalytical Chemistry | Year: 2014

Laser-ablation electrospray ionization (LAESI) mass spectrometry imaging (MSI) does not require very flat surfaces, high-precision sample preparation, or the addition of matrix. Because of these features, LAESI-MSI may be the method of choice for spatially-resolved food analysis. In this work, LAESI time-of-flight MSI was investigated for macroscopic and microscopic imaging of pesticides, mycotoxins, and plant metabolites on rose leaves, orange and lemon fruit, ergot bodies, cherry tomatoes, and maize kernels. Accurate mass ion-map data were acquired at sampling locations with an x-y center-to-center distance of 0.2-1.0 mm and were superimposed onto co-registered optical images. The spatially-resolved ion maps of pesticides on rose leaves suggest co-application of registered and banned pesticides. Ion maps of the fungicide imazalil reveal that this compound is only localized on the peel of citrus fruit. However, according to three-dimensional LAESI-MSI the penetration depth of imazalil into the peel has significant local variation. Ion maps of different plant alkaloids on ergot bodies from rye reveal colocalization in accordancewith expectations. The feasibility of using untargeted MSI for food analysis was revealed by ion maps of plant metabolites in cherry tomatoes and maize-kernel slices. For tomatoes, traveling-wave ion mobility (TWIM) was used to discriminate between different lycoperoside glycoalkaloid isomers; for maize quadrupole time-of-flight tandem mass spectrometry (MS-MS) was successfully used to elucidate the structure of a localized unknown. It is envisaged that LAESI-MSI will contribute to future research in food science, agriforensics, and plant metabolomics. © The Author(s) 2014. Source


Kok E.J.,RIKILT Wageningen UR | Pedersen J.,Technical University of Denmark | Onori R.,Istituto Superiore di Sanita | Sowa S.,Polish Institute of Plant Breeding and Acclimatization | And 3 more authors.
Trends in Biotechnology | Year: 2014

The principles for the safety assessment of genetically modified (GM) organisms (GMOs) are harmonised worldwide to a large extent. There are, however, still differences between the European GMO regulations and the GMO regulations as they have been formulated in other parts of the world. One of these differences relates to the so-called 'stacked GM events', that is, GMOs, plants so far, where new traits are combined by conventional crossing of different GM plants. This paper advocates rethinking the current food/feed safety assessment of stacked GM events in Europe based on an analysis of different aspects that currently form the rationale for the safety assessment of stacked GM events. © 2013 Elsevier Ltd. Source


Lehotay S.J.,U.S. Department of Agriculture | Sapozhnikova Y.,U.S. Department of Agriculture | Mol H.G.J.,RIKILT Wageningen UR
TrAC - Trends in Analytical Chemistry | Year: 2015

Although quantitative analytical methods must be empirically validated prior to their use in a variety of applications, including regulatory monitoring of chemical adulterants in foods, validation of qualitative method performance for the analytes and matrices of interest is frequently ignored, or general guidelines are assumed to be true for specific situations. Just as in the case of quantitative method validation, acceptable method performance criteria should be established for qualitative analysis purposes to suit the analytical needs for given applications, and empirical method validation should be conducted to demonstrate the qualitative performance capabilities the method. This critical review article is intended to describe and discuss recent developments with of respect to qualitative aspects in mass spectrometry, and to make recommendations for validation of qualitative methods that meet common needs for monitoring of chemical contaminants in foods. © 2015. Source


A new and improved software tool for elemental composition annotation of molecular ions detected in mass spectrometry, based on improved filtering rules followed by ultrafast querying in publicly available compound databases, is provided. Pubchem is used as a general source of 1.3 million unique chemical formulas. A plant metabolomics database containing ca. 100 ‰000 formulas is used as a source of naturally occurring compounds. Four modes with different sets of rules for heuristic filtering of candidate formulas coming from elemental composition analysis are incorporated and tested on both databases. The elemental composition analysis is then coupled to ultrafast PubChem searching based on a mass-indexed intermediate system. The performance of the filters is compared and discussed. When reactive compounds are assumed not to be present, 99.95% of the 1.3 million PubChem formulas is correctly found, while ca. 30% less formulas per mass are given compared to previously published rules. For the ca. 100 ‰000 plant metabolomics based formulas, 100% fit the improved rules. © 2014 American Chemical Society. Source


Ludwig S.K.J.,RIKILT Wageningen UR | Van Ginkel L.A.,RIKILT Wageningen UR | Van Ginkel L.A.,EU Reference Laboratory | Nielen M.W.F.,RIKILT Wageningen UR | Nielen M.W.F.,Wageningen University
TrAC - Trends in Analytical Chemistry | Year: 2014

There are similarities between sports doping and veterinary control. Prohibited substances (e.g., anabolic agents and peptide hormones) are similar, and immunoassays and chromatography-mass spectrometry are applied as analytical methods in both worlds. In recent years, detection strategies based on protein biomarkers were successfully developed and adopted in sports control. When measuring biomarkers, the window of detection can be extended due to a prolonged biological response, so a whole range of substances may be tackled in an indirect manner. In view of the similarities in intended biological effects, such as increased muscle mass, we envisage that biomarker-based detection may be adopted veterinary control in future. In this review, we discuss detection strategies based on protein biomarkers for biomarker discovery and method development. With the lessons learnt from successfully implementing biomarker strategies in doping regulations, we advocate adoption in the veterinary world and revision of the current restrictive regulations concerning analytical methods. © 2014 Elsevier Ltd. Source

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