Keywords: Analytical methods, Directives, Precision data, Process capability index, Tolerances.

The directives for fertilizer legislation in the European Community contain tolerance limits and methods for their control. Unfortunately, none of these methods is provided with precision data. This gap needs to be closed. Also, this collection of official methods has not been revised since its implementation. There is thus a need for adaptation to the technical progress in analytical chemistry. According to the 'New Approach' of the EC, both revision and elaboration of precision data will be done by a standardisation body (CEN). The elaborated precision data will assist the checking of the methods for their compatibility with the existing tolerance limits. A statistical approach will help in obtaining a measure for the minimum requirement for analytical precision considering the existing tolerances. Examples for the known precision data of selected ISO methods show that in some cases difficulties could arise.

Dr. Vilmos Czikkely, BASF Aktiengesellschaft GmbH, CAD/DT - M 505, Ludwigshafen, Germany

22 Pages, 6 Tables, 17 References.