|ISBN (pdf):||978-952-11-4429-5|| |
|Julkaisusarja ja numero:||Reports of the Finnish Environment Institute 5/2015|| |
|Kustantaja:||Finnish Environment Institute|| |
|Saatavuus (pdf):||http://hdl.handle.net/10138/153554|| |
|Tekijät:||Jari Nuutinen; Riitta Koivikko; Mirja Leivuori; Markku Ilmakunnas
Proftest SYKE carried out the proficiency test (PT) for analysis of oil hydrocarbons in water and soil in November-December 2014. Three types of samples were delivered to the participants; synthetic sample, surface water and soil samples. In total, 15 laboratories participated in the PT. The evaluation of the performance was based on the z scores. In this proficiency test 77 % of the data was regarded to be satisfactory when the deviation of 20 to 40 % from the assigned value was accepted. Either the calculated concentration, robust mean, mean or median of the results reported by the participants was chosen to be the assigned value depending on the analyte. The uncertainty for the assigned value was estimated at the 95 % confidence interval and for calculated assigned values it was 1.9–3.5 %, for assigned values based on the robust mean it was 15.5 %, for assigned values based on the mean it varied from 3.3 to 20.9 %, and for median based assigned value the uncertainty for the assigned value was estimated to 22.3 %.