Interlaboratory Proficiency Test 10/2018 - Metals in waste water and compost

Proftest SYKE carried out the proficiency test (PT) for analysis of elements in waters and compost material in October November 2018. The measurands for the synthetic and waste water samples were: Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, Stot, V, and Zn. For the compost sample the measurands were: As, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Ntot, Ni, Ptot, Pb, Stot, V, and Zn. In total 21 laboratories participated in the PT. In total, 90 % of the results evaluated with z scores were satisfactory when total deviation of 10–25 % from the assigned value was accepted. From the results evaluated with En scores, 72 % were satisfactory. Basically, either the metrologically traceable concentration, calculated concentration, the robust mean, the mean or the median of the results reported by the participants was used as the assigned value for measurands. Warm thanks to all the participants of this proficiency test

Interlaboratory comparison 15/2018 - Soil improver maturity test

Evira and Proftest SYKE carried out this interlaboratory comparison in May 2018 for assessing phytotoxicity, chemical composition and maturity of green waste and sewage sludge compost samples. In total 11 participants took part. Participants measured altogether 14 measurands, which are used for determining composition, phytotoxicity, stability and maturity of soil improvers, caused for instance by ammonia, ethylene oxide or short chain fatty acids. The mean of the results reported by the participants was chosen to be the assigned value for the measurands. The performance of the participants was evaluated by using z scores. In this interlaboratory comparison, 96 % of the results were satisfactory when deviation of 1 pH units and 25–80 % (for other measurands) from the assigned value was accepted. According to the results, many participants have good practices and manage these analyses well. Some participants still need more experience. More detailed guidance on procedures that may affect the results is needed. Warm thanks to all the participants of this interlaboratory comparison