The comparison CCQM-K43.1, arsenic, mercury, selenium and methylmercury in marine fish (swordfish), was organized by the inorganic analysis working group (IAWG) of CCQM as a subsequent key comparison of CCQM-K43. The National Metrology Institute of Japan (NMIJ) is the coordinating laboratory for this subsequent key comparison. Nine NMIs and one unofficial institute participated in CCQM-K43.1. The data of the unofficial institute were treated as reference data. All participants were allowed to choose the measurands (arsenic, mercury, selenium and methylmercury) of their interest. For measurement of arsenic, mercury and selenium, different measurement methods (IDMS, ICP-MS, AAS and INAA) were used and all participants with one exception used microwave digestion methods. For measurement of methylmercury, all participants used IDMS and different extraction methods (microwave, mechanical shaker and ultrasonic) were used. Most results agreed well with one or two apparent outlier(s) for arsenic and selenium. The agreement of measurement results between NMIs is very good for mercury and methylmercury.

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The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).