An Evaluation of the Inter‐Method Discrepancies in Ferromanganese Nodule Proficiency Test GeoPT 23A |
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| Authors: | Cornelia Kriete |
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| Institution: | Federal Institute for Geosciences and Natural Resources, Stilleweg 2, D‐30655 Hannover, Germany |
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| Abstract: | Round 23 of the GeoPT international proficiency testing scheme included the ferromanganese nodule powder FeMn‐1 which was distributed as an additional sample (23A). The aim of this initiative was to assess overall analytical performance for such a challenging oxide matrix with a view to the possible certification of such a material in accordance with ISO Guide requirements. To investigate inter‐method discrepancies, precision data and the method means for the most frequently used analytical methods (XRF, ICP‐MS and ICP‐AES) and sample preparation techniques were calculated and then compared using statistical tests of equivalence. For most major elements, XRF and ICP‐AES data dominated and these were found to give equivalent results. In contrast, for most trace elements significant discrepancies were detected between data obtained by different analytical methods. Possible causes are discussed with a view to attributing their origin to calibration strategy, sensitivity or interferences. It is assumed that the unusual oxide matrix generated unexpected interferences and thus method bias. Discrepancies observed between data from different analytical methods provide valuable information for the participating analysts, helping them to avoid systematic errors and thus minimising bias. They also suggest actions necessary to improve results for any future certification of such a material. |
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| Keywords: | proficiency test ferromanganese nodule equivalence of analytical methods reference material test de capacité nodules ferro‐mangané sifè re é quivalence des mé thodes d’ analyse maté riel de ré fé rence |
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