Van Harreveld Anton P, Mannebeck Dietmar, Maxeiner Björn
Odournet S.L, Barcelona 08017, Spain.
Water Sci Technol. 2009;59(8):1649-55. doi: 10.2166/wst.2009.122.
The technical standard for dynamic olfactometry EN13725:2003 is now widely applied in testing of odours for environmental management purposes. Many laboratories working in this field apply QA/QC systems according to ISO17025 and are accredited under international accreditation, e.g. European Accreditation and NATA (Australia). One of the key elements of the EN13725 standard is the requirement to attain defined levels of statistical performance parameters, in particular Precision under repeatability conditions r and Accuracy A. For the reference odour n-butanol laboratories can establish these performance characteristics in-house, through internal QA/QC measurements. However, the real proof of the pudding is to demonstrate compliance with the requirements in externally organised blind proficiency testing. Proficiency testing for olfactometry has been used since the mid 1980s in the Netherlands and Germany. Currently international proficiency tests are organised by private firm Olfatec, under EN ISO/IEC 17020:2004 accreditation. In 2007 the most recent test was held, with 29 laboratories participating in the extended proficiency test using n-butanol. Of the participating laboratories 12 fully complied with the statistical performance criteria of EN13725. This result confirms that the EN13725 performance criteria are attainable in practice. It also shows that the majority of laboratories claiming to work according to EN13725 actually fail to do so on the key issue of the performance characteristics, a key element of the EN13725 standard. Even more worrying is that among the laboratories that fail to attain the required performance, many are accredited under ISO17025. Of 36 accredited laboratories for olfactometry in Europe only 12 have demonstrated compliance in 2007. This situation may create a false sense of security among users of the data produced, trusting that they can apply uncertainties according to EN13725 while in fact the uncertainty can be larger. It is therefore very important that corrective actions are implemented, and that the accreditation organisations monitor the implementation and also ensure that all laboratories claiming to work according to EN13725 under ISO17025 accreditation actually are able to attain the minimum criteria for precision and accuracy in successive proficiency tests. For users of olfactometry results it must be absolutely clear that a laboratory working according to EN13725 under ISO17025 accreditation will deliver results with a defined and satisfactory uncertainty. Such laboratories must be able to consistently pass proficiency tests for olfactometry. Accreditation bodies are the key guardians of this reasonable expectation..
动态嗅觉测定法的技术标准EN13725:2003目前广泛应用于环境管理目的的气味测试。该领域的许多实验室都按照ISO17025应用质量保证/质量控制体系，并获得国际认可，如欧洲认可和澳大利亚国家测试机构协会（NATA）的认可。EN13725标准的关键要素之一是要求达到规定水平的统计性能参数，特别是重复性条件下的精密度r和准确度A。对于参考气味正丁醇，实验室可以通过内部质量保证/质量控制测量在内部确定这些性能特征。然而，真正的检验是在外部组织的盲态能力验证中证明符合要求。自20世纪80年代中期以来，荷兰和德国就一直使用嗅觉测定法的能力验证。目前，国际能力验证由私人公司Olfatec按照EN ISO/IEC 17020:2004认可进行组织。2007年举行了最近一次测试，有29个实验室参加了使用正丁醇的扩展能力验证。在参与测试的实验室中，有12个完全符合EN13725的统计性能标准。这一结果证实了EN13725的性能标准在实际中是可以达到的。这也表明，大多数声称按照EN13725工作的实验室在性能特征这一EN13725标准的关键要素上实际上并未做到。更令人担忧的是，在未能达到要求性能的实验室中，许多都获得了ISO17025认可。在欧洲36个获得嗅觉测定法认可的实验室中，2007年只有12个证明符合要求。这种情况可能会在数据使用者中造成一种错误的安全感，他们相信可以根据EN13725应用不确定度，而实际上不确定度可能更大。因此，实施纠正措施非常重要，认可组织要监督措施的实施，并确保所有声称在ISO17025认可下按照EN13725工作的实验室在后续能力验证中实际能够达到精密度和准确度的最低标准。对于嗅觉测定法结果的使用者来说，必须绝对清楚的是，在ISO17025认可下按照EN13725工作的实验室将提供具有明确且令人满意的不确定度的结果。这样的实验室必须能够始终通过嗅觉测定法的能力验证。认可机构是这种合理期望的关键守护者。
