Sammendrag
21 laboratories from 13 countries accepted the invitation to join the ICP Waters chemical intercomparison and successfully
reported results. The lower number of participants this year likely resulted from the global covid-19 pandemic, leading to the
lockdown of several nations during the spring of 2020. Two sets of samples were prepared and successfully distributed to the
participants: one for the determination of ions and one for the metals. In general, the results were good with an overall
acceptance of 80% (± 20% of the “true value”, and for pH and conductivity ± 0.2 pH units and ± 10%, respectively). The highest
acceptances (> 90%) were obtained for some of the ions and metals, with a maximum of 100% for sodium. This year, the
acceptance for pH was also very good (75%). The lowest acceptance rate was for total phosphorus with only 18% of the results
being accepted. However, most laboratories reported the concentration of total phosphorous to zero. A relatively low acceptance
was also achieved for alkalinity which likely resulted from the large number of different titration methods used by the
participating laboratories. General trends in the choice of techniques continue to shift towards plasma from atomic absorption,
and to mass detection from ionic emission. This is especially promising for the determination of metals at low levels.
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