17th Needle/Leaf Interlaboratory Comparison Test 2014/2015

Wien

2015

40 S. + Annex-Results

Monographie

978-3-902762-37-5

187806

54 laboratories in 25 countries participated in the 17th Needle/Leaf Interlaboratory Test. A new system for qualification and re-qualification started with the 11th test in 2009. This system was enlarged after the manual update in 2010 to all ICP-Forests partners (see König et al. 2010, 2013, Rautio et al. 2010, 2013, Pitman et al. 2010). With the ring test report each participant get a qualification report, the download is possible on the webpage (http://bfw.ac.at/ws/ring_nadel.login). It has been decided to qualify the results of each parameter separately. If 50% or more (generally two, three or all four samples) of the results for this parameter for all the samples of the ring test are within the tolerable limits, the laboratory is qualified. Re-qualification is mandatory for all ICP-Forests laboratories, if monitoring results (foliage, litterfall, ground vegetation) will be submitted to PCC in autumn 2015 from the vegetation period 2014. New since the 14th Interlaboratory Test is the usage of maximum acceptable limits of quantification (LOQ). These limits are needed, because a lot of laboratories are using multielement methods (mostly ICP-AES) with higher LOQs for some elements. But for evaluating and classification of the monitoring samples real measured results and lower LOQ are needed. A task was given from the 12th Expert Panel Meeting Foliage and Litterfall (Tallinn 2011) to the Working Group QA/QC in Laboratories to fix this problem. Maximum acceptable LOQs for mandatory and optional parameters for foliage, litterfall and ground vegetation were discussed and accepted in the 3rd Meeting of the Heads of the Laboratories (Arcachon 2011). This problem is more or less fixed now - only two laboratories submit higher LOQs than the maximum acceptable. In case of very low concentrations of copper, cadmium and lead in the interlaboratory comparison test samples, results of these samples will be excluded from the evaluation (this happened for the lead results of the samples 4). This procedure is needed to avoid wrong qualification results influenced by inaccurate measurements - and on the other hand there is no real need to detect these very low concentrations in real monitoring samples, because it gives no additional information of the nutrient status or of the pollution impact situation. In general are the results of the 17th Needle/Leaf Interlaboratory Test not so good and similar to the test before. But this is mostly influenced by few participants with methodical problems or lower experience in this working field. The following participating laboratories with a lower percentage of correct results (less than 80%) have bigger QC/QA-problems in their laboratory and/or methodical problems: A43 (78.6%), A71 (78.6%), F26 (78.6%), F06 (76.6%), F21 (70.8%), F11 (70.2%), A53 (66.7%), F29 (58.8%), A59 (58.3%), F24 (57.1%) and A83 (34.0%). An interesting point is that most of these laboratories indicate in the QA/QC questionnaire that they have control charts, but as it seems they don't use it in reality to adjust their method. Otherwise they had to detect these (sometimes) huge deviations from the target value! Some of the ICP-Forests laboratories failed and had to do a re-qualification (A47: C / A60: Pb / A62: P / F06: S, P, Mg / F24: P, K, C / F28: Mg / F29: Ca, Mg, Zn, Cu, Cd). These (ICP-Forests) laboratories had to check and re-validate their method or select another better method. If reference material is needed for this purpose - FFCC can offer some ringtest material (see: http://bfw.ac.at/rz/bfwcms2.web?dok=5146). All laboratories are invited to take part in the re-qualification program started up from now till 1st of September 2015 (see: http://bfw.ac.at/rz/bfwcms2.web?dok=7830). A clear methodical recommendation to ICP-AES can be given and, where ICP-AES is not sensitive enough, ICP-AES with ultrasonic nebulizer, ICP-MS or Flameless AAS should be used. For nitrogen and carbon, element analyzers are the best choice, if a correct calibration is performed.