Proficiency testing field studies

The test material is chosen to fulfill the aims of the study. In a proficiency testing scheme or a method validation study, the test material is usually as near as possible to typical field samples. There is no advantage in competently analyzing an artificial sample if the same laboratory has difficulty with real samples. The organizing laboratory must know the composition of the test material, and must be sure that the analyte for which a quantity is to be measured is present in about the desired amount. For pure materials this is not a problem, but for natural test materials or complex matrix materials, the organizing laboratory may have to do some analyses before the samples can be sent out to the participants. If the value of the measurand is to be established by an independent laboratory before the study, then the identity requirement is also fulfilled when the measurand is stated. 

We acknowledge financial support from the Sixth Framework Programme of the European Union (Contract SSPI-CT-2003-502492 http //www.swift-wfd.com). We also thank Nel Frijns and the RIZA monitoring team in Eijsden (The Netherlands), the local Environmental Agency (in the Aller) for permission to work. Finally, we thank all the partners in the SWIFT-WFD consortium who carried out reference measurements, prepared the reference materials, participated in the proficiency testing and in field studies. 

In the field of QA/QC the network will check regularly on the availability of methods for high-priority substances and their validation status, and initiate, whenever necessary, the organisation of interlaboratory studies for specific emerging substances. QA/QC information, such as available reference materials, proficiency testing schemes and training programmes for laboratories will be circulated. 

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