DIN CEN/TS 16490:2013-06

In Regulation (EC) No. 2003/2003 tolerance limits are mentioned for nutrient contents in mineral fertilizers (Annex II) as well as prescribed methods for control purposes (Annex IV). Prior to the work done by CEN/TC 260 following Mandate M/335, no statistical data were available for the official analytical methods to be applied. Due to the standardization work done for this mandate, statistical data have been generated. Ring testing was a major topic in this mandate. This Technical Specification describes to what extent the presently applied tolerances are in line with the obtained precision data from the analytical methods studied. The purpose of this document is to give feedback on the applied tolerances within Regulation (EC) No. 2003/2003 based on the method evaluation done as an outcome of the work executed by CEN/TC 260/WG 7 according to Mandate M/335. Following a request from the European Commission (Mandate M/418), an evaluation was done of the existing tolerances as per Regulation (EC) No. 2003/2003. As to exclude eventual interference from effects due to inhomogeneity of physically blended grades, no blends have been included in the ring tests; test samples have been limited and chosen as to be representing some main product grades sold within the EU. The statistical evaluation has been done in line with ISO 5725-2 and whenever deemed necessary for appropriate evaluation and interpretation of the test results, some extra statistical evaluation was made on the test data. As to judge to what extent problems arise in case of enforcement controls, some field data have been analysed as to verify to what extent actual conflicts exist in between test results from official controls and applied tolerances. The evaluation revealed no real need for adjustments to tolerances as they relate to analytical variability. However, it should be emphasised that the tolerances given in Regulation 2003/2003 relate not only to analytical variability but to the total variability including allowances for sampling error and product variability. Finally if the European Commission sees the necessity of further method improvements, then one could consider a project entitled to develop an alternative method. Only following a full evaluation including ring testing, a final judgment can be made if the newly developed method could be a candidate for replacement of the existing one(s) assuming better accuracy data. The Technical Specification have been prepared by CEN/TC 260 "Fertilizers and liming materials" (secretariat: DIN). The national mirror committee is Working Committee NA 057-03-02 AA "Düngemittel" ("Fertilizers") of NAL.