Forest Foliar Co-ordinating Centre (FFCC)
Limits for the interlaboratory comparison test evaluation
In the agreements of the Meetings of the Expert Panel Foliage and Litterfallin As (1994), Vienna (1997), Bonn (1999), Prague (2003),  Madrid (2007) and Hamburg (2009) and in the 3rd Meeting of the Heads of the Laboratories the following tolerable limits, maximum acceptable limits of quantification and the lowest evaluated result for foliage ringtest samples were fixed:

With beginning of the 14th Needle and Leaf Interlaboratory Test a laboratory will pass the test if a LOQ is reported only if:
  • the LOQ is equal or lower than the max. tolerable LOQ (see table)
  • the reported LOQ is within the tolerable limits (lower limit) for the parameter.
This procedure is needed to exclude laboratories and parameters with very high LOQ from the qualification report and to force the laboratories to use adequate instrumentation for their foliage, litterfall and ground vegetation surveys.

If the outlier free mean (or the median) for the sample is lower than the lowest evaluated result, this sample is not used in the qualification report. This procedure is needed because:
  • the concentration is too low to detect it accurate from the participating laboratories (this influence the calculation of the outlier free mean) and
  • the result give no practical relevant information of the nutrient status (Cu: deficency) or of the pollution impact situation (Cd, Cu, Pb : not polluted) of real monitoring samples.

Up from the 19th Needle/Leaf Interlaboaratory Test preliminary limits for some heavy metals were used for the evaluation:

26.01.16 | Fürst, A.
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