Inter-laboratory Comparison Study of a Reference Material for Nutrients in Seawater

Aoyama, M., Anstey, C., Barwell-Clarke, J., Baurand, F., Becker, S., Blum, M., Coverly, S. C., Czobik, E., dfAmico, F., Dahllof, I., Dai, M., Dobson, J., Pierre-Duplessix, O., Duval, M., Engelke, C., Gong, G.-C., Grosso, O., Hirayama, A., Inoue, H., Ishida, Y., Hydes, D. J., Kasai, H., Kerouel, R., Knockaert, M., Kress, N., Krogslund, K. A., Kumagai, M., Leterme, S. C., Mahaffey, C., Mitsuda, H., Morin, P., Moutin, T., Munaron, D., Murata, A., Nausch, G., Ogawa, H., van Ooijen, J., Pan, J., Paradis, G., Payne, C., Prove, G., Raimbault, P., Rose, M., Saito, K., Saito, H., Sato, K., Schmidt, C., Schutt, M., Shammon, T. M., Olafsdottir, S., Sun, J., Tanhua, Toste, Weigelt-Krenz, S., White, L., Woodward, E. M. S., Worsfold, P., Yoshimura, T., Youenou, A. and Zhang, J.-Z. (2008) Inter-laboratory Comparison Study of a Reference Material for Nutrients in Seawater Technical Reports of the Meteorological Research Institute, 60 . Meteorological Research Institute, Tsukuba, Japan.

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Autoclaved natural seawater collected in the North Pacific Ocean was used as a reference material for nutrients in seawater (RMNS) during an inter-laboratory comparison (I/C) study conducted in 2008. This study was a follow-up to previous studies conducted in 2003 and 2006. A set of six samples was distributed to each of 58 laboratories in 15 countries around the globe, and results were returned by 54 of those laboratories (15 countries). The homogeneities of samples used in the 2008 I/C study, based on analyses for three determinants, were improved compared to those of samples used in the 2003 and 2006 I/C studies.
Results of these I/C studies indicate that most of the participating laboratories have an analytical technique for nutrients that is sufficient to provide data of high
comparability. The differences between reported concentrations from the same laboratories in the 2006 and 2008 I/C studies for the same batch of RMNS indicate that
most of the laboratories have been maintaining internal comparability for two years.
Thus, with the current high level of performance in the participating laboratories, the use of a common reference material and the adaptation of an internationally accepted
nutrient scale system would increase comparability among laboratories worldwide, and the use of a certified reference material would establish traceability.
In the 2008 I/C study we observed a problem of non-linearity of the instruments of the participating laboratories similar to that observed among the laboratories in the 2006 I/C study. This problem of non-linearity should be investigated and discussed to
improve comparability for the full range of nutrient concentrations. For silicate comparability in particular, we see relatively larger consensus standard deviations than
those for nitrate and phosphate.

Document Type: Report (Research Report)
Keywords: Marine chemistry; nutrients; seawater
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
ISSN: 0386-4049
Date Deposited: 01 Dec 2010 14:17
Last Modified: 18 Jul 2013 08:48

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