Certification of Matrix Reference Materials in Chemical Measurement: A New Basis for Adopting a Consensus Value Derived from a Proficiency Test

ISO Guide 35 (2017) specifies conditions for the certification of matrix reference materials via information from proficiency tests. Many scientists involved in the provision of proficiency tests for analytical chemistry have concluded that the Guide 35 conditions are effectively fulfilled by identifying certified values with properly-derived consensus values. However, the claim that such reference materials are ‘certified’ is likely to be challenged by traditional metrologists. This paper proposes to move beyond this unresolved situation to put certification via proficiency testing on an unassailable footing. The proposal therefore is not a questionable fulfilment of the Guide 35 conditions but an unrelated paradigm for certification.