Proficiency testing as the key element in implementing EN13275 olfactometry

摘要

The technical standard for dynamic olfactometry EN13725:2003 is now widely applied in testingnof odours for environmental management purposes. Many laboratories working in this field applynQA/QC systems according to ISO17025 and are accredited under international accreditation, e.g.nEuropean Accreditation and NATA (Australia). One of the key elements of the EN13725 standardnis the requirement to attain defined levels of statistical performance parameters, in particularnPrecision under repeatability conditions r and Accuracy A. For the reference odour n-butanolnlaboratories can establish these performance characteristics in-house, through internal QA/QCnmeasurements. However, the real proof of the pudding is to demonstrate compliance with thenrequirements in externally organised blind proficiency testing. Proficiency testing for olfactometrynhas been used since the mid 1980s in the Netherlands and Germany. Currently internationalnproficiency tests are organised by private firm Olfatec, under EN ISO/IEC 17020:2004naccreditation. In 2007 the most recent test was held, with 29 laboratories participating in thenextended proficiency test using n-butanol. Of the participating laboratories 12 fully complied withnthe statistical performance criteria of EN13725. This result confirms that the EN13725nperformance criteria are attainable in practice. It also shows that the majority of laboratoriesnclaiming to work according to EN13725 actually fail to do so on the key issue of the performancencharacteristics, a key element of the EN13725 standard. Even more worrying is that among thenlaboratories that fail to attain the required performance, many are accredited under ISO17025. Ofn36 accredited laboratories for olfactometry in Europe only 12 have demonstrated compliance inn2007. This situation may create a false sense of security among users of the data produced,ntrusting that they can apply uncertainties according to EN13725 while in fact the uncertainty cannbe larger. It is therefore very important that corrective actions are implemented, and that thenaccreditation organisations monitor the implementation and also ensure that all laboratoriesnclaiming to work according to EN13725 under ISO17025 accreditation actually are able to attainnthe minimum criteria for precision and accuracy in successive proficiency tests. For users ofnolfactometry results it must be absolutely clear that a laboratory working according to EN13725nunder ISO17025 accreditation will deliver results with a defined and satisfactory uncertainty. Suchnlaboratories must be able to consistently pass proficiency tests for olfactometry. Accreditationnbodies are the key guardians of this reasonable expectation..