Conversion Factors e-learning
Click here to enter: E-LEARNING
The MRL residue definition for some pesticides includes not only the parent compound, but also its metabolites or other transformation products. This means that when reporting a concentration result value, its residue definition should be taken into account.
Through the experience gained with the EUPTs, involving more than 150 participant laboratories, it has been noticed that some of them do not apply conversion factors properly. It is because of this, that the European Union Reference Laboratories have found useful to create an e-learning tool to help the laboratories to calculate the concentration of those multicomponent pesticide residue definitions.
When expressing the concentration of those pesticides, conversion factors should be borne in mind, as they have to be applied for each one of the components in the definition. In those cases, the total concentration can be obtained by different ways, depending on the residue definition.
When this one refers only to the "sum of components" (eg Triadimenol and Triadimefon, sum of triadimenol and triadimefon), the conversion factor is one, which is why for practical purposes the final result will be the addition of the components.
But when the definition includes the term "expressed as" (eg Carbofuran, sum of carbofuran and 3-hydroxycarbofuran expressed as carbofuran), conversion factors should be calculated by adjusting the concentration according to the different molecular weight of the components.
Another particular case is the one of Methomyl and Thiodicarb (sum of methomyl and thiodicarb expressed as methomyl). In this specific example, stoichiometry has to be applied to the calculus of the concentration, and the conversion factor of thiodicarb has to be multiplied by two.
This way the e-learning offers a very useful tool for the familiarization with the conversion factor calculus. In a first step we have included those multicomponent residue definitions included in the EU Multi-annual Control Programme (Commission Implementing Regulation (EU) No 1274/2011 of 7 December 2011 concerning a coordinated multiannual control programme of the Union for 2012, 2013 and 2014 to ensure compliance with maximum residue levels of pesticides and to assess the consumer exposure to pesticide residues in and on food of plant and animal origin), but only multiresidue method amenable pesticides for fruits and vegetables are included, in a near future this list will be increased with more other multicomponent residues.
Click here to enter: E-LEARNING
Published 08-05-2012, 10:55:27
Share: 
