GeoPT3. International proficiency test for analytical geochemistry laboratories - Report on round 3

Results from seventy two laboratories participating in GeoPT3, round three of the international proficiency testing programme for analytical geochemis try laboratories, are presented. The report includes analytical results con tributed by participating laboratories, together with the z-scores derived from these results using appropriate fitness for purpose criteria. These da ta are available for use as part of the laboratories' quality control proce dures to assess the reliability of analysed results.