Aims and principles

Improvement schemes can be defined as a succession of individual interlaboratory studies in which several laboratories analyse the same test samples for the same characteristics (usually the content of an analyte), following a similar protocol, to validate each individual step of their own analytical method in order to eliminate all sources of systematic errors [5] 

Besides the classical interlaboratory studies, improvement schemes enable laboratories to develop and validate all steps of new or existing analytical procedure(s) in adequately organised successive exercises. Improvement schemes may be considered as preliminary studies for laboratory or method performance studies or certification of reference materials [5]. Such programmes are very valuable when the analytical procedures include several complex and critical steps, e.g. for the determination of trace organic compounds or chemical species. They require a long term involvement of the organiser and participants, as well as investment of resources. 

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A written major-accident prevention policy has been established that includes the operator s overall aims and principles of action with respect to the control of major-accident hazards. 

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