CEN methods

The assessment of validation data of CEN methods does not differ significantly from other validation schemes. The most important quantitative performance characteristics are trueness and precision. Additionally, some information about sensitivity... 

In Europe, very different concepts of method validation are in use. The extent of validation depends upon legal requirements (e.g., for enforcement methods provided by the applicant), upon the required level of acceptance (e.g., for CEN methods) and upon national resources. Undoubtedly, the best method validation is performed with the help of inter-laboratory studies of performance, but such studies can be uneconomic, too slow to reach completion or restricted in scope. 

The integration of analytical methods in European standards requires their acceptance by several national experts within special working groups and in a final weighted vote of National Standards Bodies. Therefore, there needs to be very high confidence in the performance of methods. Consequently, methods should be tested in inter-laboratory method validation studies, with the exception of those multiresidue methods which are widely used throughout Europe. In the case of CEN methods there is no doubt about residue definition but detailed requirements about the number of matrices and concentration levels in validation experiments do not exist. Eor this reason it may be that CEN methods are validated for important crops only. 

There are other international standardising organisations, most notably the European Committee for Standardization (CEN) and AOACI, which follow similar requirements. Although CEN methods are not prescribed by legislation, the European Commission places considerable importance on the work that CEN carries out in the development of specific methods in the food sector CEN... 

The time and temperature conditions that must be chosen to mimic contact with the food are regulated for plastics in Directives 82/711/EEC (basic rules), 93/8/EEC (basic rules, 1st amendment) and 97/48/EC (basic rules, 2nd amendment). Additional information can be found in CEN methods for overall migration (EN 1186-1 2002) and specific migrations (EN 13130-1 2005). In many cases national legislation also applies the use of such simulants, temperature and time conditions, to other, non-plastic, food contact materials. Eor ceramics a specific time/temperature/food simulant has been chosen 22 °C for 24 hours using 4% acidic acid as food simulant regardless of the real-life application, as described in Directives 84/500/EEC and 2005/ 31/EC. 

Besides the above there are many more sources of possible error. More detailed information about the determination of overall migration can be found in CEN methods, which are listed in Table 5.3. The use of olive oil is preferred over the use of alternative simulants because in most cases 95% ethanol or isooctane is a more stringent simulant resulting in a much higher value of overall migration than the value that would be obtained when olive oil is used. 

Table 5.3 The official CEN methods to determine overall migration...

General information about how to determine specific migration is available in CEN document EN 13130-1 2004 Materials and articles in contact with foodstuffs - Plastics substances subject to limitation - Part 1 Guide to test methods for the specific migration of substances from plastics to foods and food simulants and the determination of substances in plastics and the selection of conditions of exposure to food simulants . CEN has also established methods for the determination of some specific migration. Table 5.4 is a list of components for which CEN methods are established. Another source of methods for the determination of specific migration can be found at http // cpf.jrc.it/smt/. At this website of the Joint Research Centre methods are collected and made public online. A summary of the methods available at the website of JRC is given in Table 5.5. 

Analytical method ISO/CEN method or national or other method and description of the method used WFD, SOE Cat. 2... 

Quality eontrol in the 80/778/EEC DWD was restrieted to the mention of analytical reference methods. The eiurent DWD goes mueh further by making ISO/CEN methods eompulsory and defining performanee eriteria for (mostly) chemico-physical parameters. Furthermore, member states need to have some QC/QA system in place in the approved laboratories for drinking water analyses. At the time of adoption of the DWD it was not judged possible to apply an aeereditation system for all member states, but it is expeeted that this will be an additional requirement in the near future. 

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