Lykkeberg, Anne Kruse

Poulsen, Mette Erecius

Rasmussen, Peter Have

Online Research Database In Technology

                       General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.  • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal   If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.     Downloaded from orbit.dtu.dk on: Dec 20, 2017Development of a LC-QTOF screening method for pesticides and mycotoxins incerealsLykkeberg, Anne Kruse; Rasmussen, Peter Have; Poulsen, Mette EreciusPublication date:2014Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Lykkeberg, A. K., Rasmussen, P. H., & Poulsen, M. E. (2014). Development of a LC-QTOF screening methodfor pesticides and mycotoxins in cereals. Poster session presented at 10th European Pesticide ResidueWorkshop, Dublin, Ireland.Development of a LC-QTOF screening method for pesticides and mycotoxins in cereals Anne Kruse Lykkeberg, Peter Have Rasmussen and Mette Erecius Poulsen DTU National Food Institute, Moerkhoej Bygade 19, DK-2860 Soeborg, Denmark; e-mail : alyk@food.dtu.dk 1 EURL-CF: EU Reference Laboratory for pesticide Residues in Cereals and Feeding stuff . DTU National Food Institute, Moerkhoej Bygade 19, DK-2860 Soeborg, Denmark   e-mail :  eurl-cf@foood.dtu.dk,  www.eurl-pesticides.eu   Introduction: The EURL for Pesticide residues in Cereals and Feeding stuff1 has today a pesticide screening method using LC-QTOF (Agilent) with a database containing retention times of around 600 pesticides injected into the instrument. Other contaminants in cereals might also be relevant to include e.g. mycotoxins produced by fungi, which can arise at the field or during storage of cereals.   The aim of this project was to include relevant mycotoxins into the current pesticide screening method. In this study extraction and clean up of 25 mycotoxins and other secondary metabolites were investigated simultaneously together with selected pesticides. Recovery and matrix effect during the QuEChERS method were investigated.  01002003004005006007008009000 2 4 6 8 10 12 14 16 18m/z Retention time Positive mode ExtractionPhase separationFreeze outPSAMycotoxinsPesticides01002003004005006007008009000 2 4 6 8 10 12 14 16 18m/z Retention time Negative mode ExtractionPhase separationFreeze outPSAMycotoxinsPesticidesExperimental: 25 mycotoxins at relevant concentration levels and 113 pesticides at 0.1 mg/kg were spiked into wheat flour (N=4). Spiked samples and blank samples were cleaned up using the QuEChERS method, and samples were taken after the 4 different steps specified in figure 1: After extraction with water and acetonitrile followed up with centrifugation (step 1), after phase separation with magnesium sulphate (step 2), after a freeze out step to remove lipids (step 3) and finally after PSA clean up (step 4). Matrix matched standards at the four steps using the blank samples and standards in solvent were prepared.  Recovery and Matrix-effect was calculated using the following equations:   𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅 =  𝐴𝑅𝑅𝐴 𝑠𝑠𝑠𝑠𝑅𝑠 𝑠𝐴𝑠𝑠𝑠𝑅𝐴𝑅𝑅𝐴 𝑠𝐴𝑚𝑅𝑠𝑚 𝑠𝑚𝐴𝑠𝑠𝐴𝑅𝑠 × 100%                                     𝑀𝐴𝑚𝑅𝑠𝑚 𝑅𝑒𝑒𝑅𝑅𝑚 = 𝐴𝑅𝑅𝐴 (𝑠𝐴𝑚𝑅𝑠𝑚 𝑠𝑚𝐴𝑠𝑠𝐴𝑅𝑠)𝐴𝑅𝑅𝐴 (𝑠𝑝𝑅𝑅 𝑠𝑚𝐴𝑠𝑠𝐴𝑅𝑠) × 100%  • Water • Acetonitrile 1. Extraction • Magnesium sulphate • NaCl, Citrate buffer 2. Phase separation • 1 h at -80 ºC • Centrifugation 3. Freeze out step • PSA  • Magnesium sulphate 4. PSA clean up Recovery Matrix-effect 1 2 3 4 1 2 3 4 MYCOTOXINS                   Fumonisin B1   96 62 35 5 71 213 204 123 Fumonisin B2   76 73 36 6 153 166 151 111 Gliotoxin   134 86 102 48 52 72 72 88 HT2   90 117 116 106 196 55 58 95 Mycophenolic acid   111 101 107 8 223 130 139 79 Nivalenol   120 58 72 66 55 60 58 88 Ochratoxin A   105 94 103 ND 107 125 130 80 Patulin   126 76 98 116 182 307 242 161 Roquefortin C   153 101 92 92 31 38 41 75 PESTICIDES                   2.4-Dimethylformanilide   162 93 102 100 27 43 50 71 Acephate(I)   119 81 85 85 12 28 32 50 Acephate(II)   114 105 80 87 80 87 94 103 Aldicarb   101 94 74 106 24 20 26 41 Amitraz   103 57 72 63 62 49 67 90 Diazinon 118 160 151 111 29 19 24 60 Difenconazole   124 95 105 113 39 64 118 101 Epoxiconazole(I) 122 112 105 110 32 28 31 74 Ethoprop 126 108 108 100 28 22 25 69 Etofenprox   100 82 95 129 518 185 171 141 Fipronil   157 107 117 124 144 182 177 121 Isoprothiolane   199 104 104 109 18 30 70 97 Kresoxim-methyl   163 86 116 90 10 19 26 56 Malathion   186 121 135 86 12 10 16 61 Metaflumizone   164 98 114 133 187 157 157 108 Metconazole   174 111 107 133 37 54 102 96 Metribuzin   123 99 112 101 62 61 63 82 Oxadixyl   158 120 111 95 54 49 65 81 Oxamyl   85 88 88 106 370 239 169 104 Phenthoate  155 72 102 105 14 37 43 67 Phosmetoxon 162 109 118 108 58 66 71 87 Phoxim   170 58 115 150 28 76 103 62 Pirimiphos-methyl  171 115 116 73 21 26 42 62 Quinoxyfen   116 106 107 98 40 39 54 77 Tebufenozide   131 85 111 134 125 207 321 202 Triazophos   183 98 101 114 19 35 81 99 Trichlorfon 307 51 97 84 12 67 68 84 Trifloxystrobin   135 117 126 116 65 57 59 81 Zoxamide   113 83 97 96 21 24 42 77 Figure 1: Overview of the QuEChERS method. Samples were taken after the four steps. Figure 3  Recovery and Matrix-effect of selected mycotoxins and pesticides. Most compounds showed acceptable recoveries at the step 2-4. Figure 2  Matrix components in wheat samples after the 4 different clean up steps. Mycotoxins and pesticdes are shown in black. Figure 4 Total Ion Chromatograms and Matrix components of Oat, Barley, Wheat and Rye after the freezings step 3. 01002003004005006007008009000 5 10 15 20Oat 7x10001122334455667+ESI TIC Scan pos_Byg Blank E.d 1 12Counts vs. Acquisition Time (min)1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1701002003004005006007008009000 5 10 15 20Barley 7x1000.11.22.33.44.55.66.+ESI TIC Scan pos_Hvede Blank E.d 1 12Counts vs. Acquisition Time (min)1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1701002003004005006007008009000 5 10 15 20Wheat 7x100011223344556677+ESI TIC Scan pos_Rug Blank E.d 1 12Counts vs. Acquisition Time (min)1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1701002003004005006007008009000 5 10 15 20Rye 7x10001122334455667788+ESI TIC Scan pos Havre blank E.d 1 12Counts vs. Acquisition Time (min)1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17Discussions: The matrix components during the four steps are illustrated in Figure 2. It shows that more and more matrix-components are removed and the final PSA clean-up step 4 really removes significant amounts of matrix. Analytes are shown in black. Recovery and matrix effect were similar in step 2-4 for most analytes, but some analytes had less matrix-effect after freezing and certainly after the PSA clean-up (Figure 3). However, several of the mycotoxins containing carboxylic acid groups are removed totally during the PSA step 3 (Figure 2). Recovery of the Fumonisins declines already after the freezing step 3. To choose the final sample preparation method a compromise is needed. Some matrix-effect is removed during the freezing step and therefore it was chosen to stop after step 3 before the PSA clean-up step 4, which removes acid analytes. Matrix components and Total Ion Chromatograms of other cereals are shown in Figure 4. It is seen that Oat and Barley has more matrix components than wheat, and therefore more matrix-effect in these cereals are expected. Conclusions: The QuEChERS method included a freezing step but without PSA clean up was chosen as the best compromise to analyse  mycotoxins and pesticides in cereals. 

Development of a LC-QTOF screening method for pesticides and mycotoxins in cereals

http://orbit.dtu.dk/ws/files/102668300/LC_QTOF_final.pdf

Development of a LC-QTOF screening method for pesticides and mycotoxins in cereals

Abstract

Similar works

Full text

Available Versions

Online Research Database In Technology