28 No. 3
The International Harmonized Protocol for the Proficiency Testing of Analytical Chemistry Laboratories (IUPAC Technical Report)
Michael Thompson, Stephen L.R. Ellison, and Roger Wood
Pure and Applied Chemistry
Vol. 78, No. 1, pp. 145–196 (2006)
For a laboratory to produce consistently reliable data, it must implement an appropriate program of quality-assurance and performance-monitoring procedures. Proficiency testing is one of these procedures. The usual format for proficiency testing schemes in analytical chemistry is based on the distribution of samples of a test material to the participants. Participating laboratories ("participants") generally know the test material has been sent by a proficiency scheme provider, but occasionally the material may be received "blind" (i.e., it is received from a normal customer of the laboratory). The participants analyze the material without knowledge of the correct result and return the result of the measurement to the scheme provider. The provider converts the results into scores that reflect the performance of the participant laboratory. This alerts the participant to unexpected problems that might be present and spurs the management to take whatever remedial action is necessary.
The ethos of this Harmonized Protocol is that proficiency testing should provide information on the fitness-for-purpose of analytical results provided by participants, to assist them in meeting requirements. This can be achieved when:
- criteria for assessing results take fitness-for-purpose into account, so that scores inform participants when they need to improve their performance to satisfy customer (or stakeholder) needs
- the circumstances of proficiency testing are close to those prevailing during routine analysis, so that the outcome represents "real life"
- the method of scoring should be simple and, where at all possible, consistent over the whole realm of analytical measurement, to ensure ready interpretation by participants and customers
While the first consideration of proficiency testing is to provide a basis for self-help for each participant, it would be disingenuous to ignore the fact that other uses are made of proficiency testing results. Participants commonly use their scores to demonstrate competence to potential customers and accreditation assessors, and this has the unfortunate effect of pressurizing analysts to excel in the proficiency tests rather than simply to assess routine procedures. Participants should make every effort to avoid such a tendency as, for the most part, it is impossible for scheme providers to detect or eliminate it. Participants must also be diligent in avoiding any misinterpretation of accumulated scores.
The international standardizing organizations—International, ISO, and IUPAC—cooperated to produce the International Harmonized Protocol for the Proficiency Testing of (Chemical) Analytical Laboratories. The working group that produced the protocol agreed to revise that protocol in light of recent developments and the experience gained since it was first published in 1993. This revision has been prepared and agreed upon in light of comments received following open consultation.
last modified 25 April 2007.
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