Title: IMEP-40: Determintion of trace elements in seawater
Publisher: Publications Office of the European Union
Publication Year: 2015
JRC N°: JRC96486
ISBN: 978-92-79-49395-9
ISSN: 1831-9424
Other Identifiers: EUR 27337
OP LA-NA-27337-EN-N
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC96486
DOI: 10.2787/805630
Type: EUR - Scientific and Technical Research Reports
Abstract: Fifty-three participants from twenty-nine countries registered to the exercise. Seven participants did not report results. The test item used was a seawater sample containing the trace elements As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se and Zn. Laboratories with demonstrated experience in the field provided results to establish the assigned values (Xref). The standard uncertainties associated to the assigned values (uref) were calculated according to ISO Guide 35. Laboratory results were rated with z- and zeta (ζ-) scores in accordance with ISO 13528. The standard deviation for the proficiency assessment, , for all elements was based on the experience in the Water Framework Directive and was set at 25 %. The trace elements were present in very low concentration levels (low μg L-1 range equal to natural contamination levels) and therefore many laboratories reported "lower than" values. The percentage of satisfactory z-scores ranged from 41 % (Cr, Fe) to 86 % (Mo). The low concentration levels of the trace elements in a difficult matrix (high saline content) need to be taken into consideration to understand the general low rate of satisfactory scores. Laboratories that score systematically too high should examine the cause of this positive bias.
JRC Directorate:Health, Consumers and Reference Materials

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