Interlaboratory Proficiency Test 05/2018 - Metals in natural waters and soil

Proftest SYKE carried out the proficiency test (PT) for analysis of elements in natural waters and soil in April-May 2018. The measurands for the synthetic, ground and lake water as well as soil samples were: Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr, Ti, V, and Zn. In addition to the aforementioned, also measurands Ca and Mg were analysed from the soil sample. In total 20 participants joined in the PT. In this proficiency test 88 % of the results were satisfactory when deviation of 10–35 % from the assigned value was accepted. Basically, either the metrologically traceable concentration, the calculated concentration, the robust mean, the mean or the median of the results reported by the participants was used as the assigned value for the measurands. The evaluation of the performance of the participants was carried out using z scores. In some cases the performance evaluation based on z scores was not possible e.g. due to the low number of the participant results or the high deviation of reported results. There, the evaluation of performance was carried out by En scores. Warm thanks to all the participants of this proficiency test