Development and independent laboratory validation of a simple method for the determination of paraquat and diquat in pot
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ORIGINAL PAPER
Development and independent laboratory validation of a simple method for the determination of paraquat and diquat in potato, cereals and pulses Diana I. S. Kolberg & Dorothea Mack & Michelangelo Anastassiades & Michael T. Hetmanski & Richard J. Fussell & Thijs Meijer & Hans G. J. Mol Received: 5 March 2012 / Revised: 26 July 2012 / Accepted: 8 August 2012 / Published online: 1 September 2012 # Springer-Verlag 2012
Abstract A new sensitive, fast and robust method for the determination of paraquat and diquat residues in potatoes, cereals and pulses is presented. Different extraction conditions (solvent, time and temperature) have been evaluated using barley grain, potatoes and dry lentils containing incurred residues of diquat and paraquat. The finalised procedure involves extraction with a mixture of methanol/water/ hydrochloric acid at 80 °C and analysis by liquid chromatography–tandem mass spectrometry. Diquat D4 and Paraquat D6 internal standards were added to the test portions prior to extraction. A small-scale inter-laboratory validation of the developed method for diquat and paraquat using potato and barley samples was conducted by three laboratories. The precision and accuracy of the method were determined from recovery experiments (five replicates) at 0.01 and 0.1 mgkg−1. The recoveries obtained (n0180) were in the range of 92–120 % with associated relative standard deviation (RSD) between 1.4–10 % for all compound/commodity/spiking concentration combinations.
Electronic supplementary material The online version of this article (doi:10.1007/s00216-012-6340-9) contains supplementary material, which is available to authorized users. D. I. S. Kolberg (*) : D. Mack : M. Anastassiades Chemisches und Veterinäruntersuchungsamt Stuttgart, Schaflandstr. 3/2, 70736 Fellbach, Germany e-mail: [email protected] M. T. Hetmanski : R. J. Fussell Fera-Food and Environment Research Agency, Sand Hutton, York YO41 1LZ, UK T. Meijer : H. G. J. Mol RIKILT-Institute of Food Safety, Akkermaalsbos 2, 6708 Wageningen, The Netherlands
Keywords Diquat . Paraquat . Potato . Cereals . Lentils . LC-MS/MS
Introduction Paraquat and diquat are broad spectrum contact herbicides, which are used in many countries for the control of weeds in agriculture and for the control of aquatic weeds. Their strong herbicidal activity combined with their high soil binding potential, which prevents their leaching into aquifers, makes them suitable for agricultural use. In the European Union (EU) diquat is used as a desiccant to facilitate mechanical harvest of many crops including potatoes, cereals (not for human consumption), canola and pulses such as soya and alfalfa. In the past, paraquat was used in many EU countries as a fast-acting non-selective herbicide. An EUwide authorisation (inclusion in Annex I of regulation 91/ 414/EEC) passed in 2003 was annulled in 2007 by the European Court of First Instance following a legal case launched by the Swedish authorities. Nonetheless, paraquat is still used on more than 100 crops in 100
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