4.1 Traceability and the Comparability of Results
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pure compounds, or chemical RMs, which enable the value of the property (the content of the chemical substance in a test sample; the identity of the substance) to be
transferred between the various institutions and reproduced in different laboratories.
Such conduct does not provide a direct reference to the international system of
units (SI) but is consistent with the requirements of ISO/IEC 17025 and policy of
accreditation bodies. When the calibration or testing cannot be done strictly in SI
units, confidence in the results of measurements is determined by:
– The use of CRMs provided by a competent supplier. The accreditation criteria for
Reference Material Producer (RMP) are given in ISO 17034:2016;
– The use of established methods and/or agreed upon references that are clearly
described and followed by all parties.
In the measurement of the chemical quantity, the result depends on the applied
measurement procedure, and the ability to compare results is often restricted to the
same measurement conditions. In addition, the implementation of traceability in the
chemical measurements is necessary to correctly define the aim of measurements,
taking into account matrix effects, the diversity of the composition of each portion of
the sample, the non-homogeneity of the test material and the stability of the sample.
4.2 General Requirements for Metrological Traceability
In order to ensure the comparability of the results given by laboratories worldwide,
the common policy should be implemented, which should follow the requirements
of ISO/IEC 17025 and ISO 15189. Such a policy is outlined in the ILAC Policy
Document P10:01/2013 ILAC Policy on the Traceability of Measurement Results.
Metrological traceability requires an unbroken chain of calibrations to stated references, all with assigned uncertainties. Within such a chain, a sequence of measurement standards and calibrations are used to relate a given measurement result to a
stated reference,
Important features of measurement traceability include:
– An unbroken chain of comparisons to international or national standards of measurement;
– Documented measurement procedure;
– Documented measurement uncertainty;
– Sound technical infrastructure and technical competence of personnel;
– A reference to SI units, measurement standards or reference measurement procedures containing units of measurement;
– Defined intervals between calibrations.
45
pure compounds, or chemical RMs, which enable the value of the property (the content of the chemical substance in a test sample; the identity of the substance) to be
transferred between the various institutions and reproduced in different laboratories.
Such conduct does not provide a direct reference to the international system of
units (SI) but is consistent with the requirements of ISO/IEC 17025 and policy of
accreditation bodies. When the calibration or testing cannot be done strictly in SI
units, confidence in the results of measurements is determined by:
– The use of CRMs provided by a competent supplier. The accreditation criteria for
Reference Material Producer (RMP) are given in ISO 17034:2016;
– The use of established methods and/or agreed upon references that are clearly
described and followed by all parties.
In the measurement of the chemical quantity, the result depends on the applied
measurement procedure, and the ability to compare results is often restricted to the
same measurement conditions. In addition, the implementation of traceability in the
chemical measurements is necessary to correctly define the aim of measurements,
taking into account matrix effects, the diversity of the composition of each portion of
the sample, the non-homogeneity of the test material and the stability of the sample.
4.2 General Requirements for Metrological Traceability
In order to ensure the comparability of the results given by laboratories worldwide,
the common policy should be implemented, which should follow the requirements
of ISO/IEC 17025 and ISO 15189. Such a policy is outlined in the ILAC Policy
Document P10:01/2013 ILAC Policy on the Traceability of Measurement Results.
Metrological traceability requires an unbroken chain of calibrations to stated references, all with assigned uncertainties. Within such a chain, a sequence of measurement standards and calibrations are used to relate a given measurement result to a
stated reference,
Important features of measurement traceability include:
– An unbroken chain of comparisons to international or national standards of measurement;
– Documented measurement procedure;
– Documented measurement uncertainty;
– Sound technical infrastructure and technical competence of personnel;
– A reference to SI units, measurement standards or reference measurement procedures containing units of measurement;
– Defined intervals between calibrations.