11th Needle/Leaf Interlaboratory Comparison Test - 2008/200956 Laboratories from 28 countries participated in this test.
4 samples were sent:
- Sample 1 (Pine branches/Finland)
- Sample 2 (Pine - Pinus brutia/Turkey)
- Sample 3 (Maple leaves /Austria)
- Sample 4 (Spruce needles/Finland) is indentical with sample 1 from the 3rd test
With the start of the Life+ Future Monitoring Project (FutMon) in the beginning of 2009, QA/QC activities are financed for all countries participating in this project. There is a new system for qualification and re-qualification planned for 2009. Together with the ringtest report each participant will receive a qualification report. It has been decided to qualify the results of each parameter separately. If 50% or more (two, three or all four samples) of the results for this parameter for all the samples of the ringtest are within the tolerable limits, the laboratory is qualified. Re-qualification is mandatory for laboratories of the FutMon partners and recommended for ICP-Forests laboratories.
In the FutMon project, litterfall and ground vegetation samples should be analysed as well, in addition to the leaf and needle samples usually analysed in the ringtest programme. Within this round, for the first time a non-foliage litterfall sample (pine branches) was sent to all laboratories. The concentrations of some elements (eg. N, S, P, Mg, K) were low and the matrix was difficult to digest (eg. Fe). Higher tolerable limits were fixed in the meetings in Hamburg 2009, taking into account the low concentration of some elements in non-foliage litterfall samples.
The results from most laboratories show a good analytical quality in foliage (and litterfall) analysis. Some of the laboratories had to learn from their ringtest results and had to improve their quality. They had to make a revision of their method, especially those with statistic outliers and/or considerable results (more than 20%) outside of the tolerable limits (especially the laboratories 80, 30, 82, 05, 15, 19, 83, 81, 72, 04a, 75, 49 and 23).
Results of the 26 "Level II - laboratories"
However, especially the results for Nitrogen, Carbon and Sulphur are sometimes bad and the concerned laboratories had to improve the quality for these elements. It seems that these laboratories have a calibration problem with their element-analyzers. An improvement is also needed for magnesium, a macro-nutrient for which the analysis is mandatory and should pose no problems.
A clear improvement in quality can be seen for the lead and cadmium results.
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