66
6 Reference Materials in Chemical Measurements
much more diversed. In this case, the specific techniques used for measurement, the
complexity and diversity of test samples and often an extremely low content of the
analyte all add to the complexity of the situation, as well as necessitate the use of a
multi-step process of sample preparation.
Reference materials (RM) and certified reference materials (CRM) are an
extremely important tool for obtaining reliable results of measurements of the
chemical quantities.
6.1 Basic Definitions and Requirements
Reference material (RM) is a generic term to describe a group of materials used
as transfer standards in chemical measurements. Transfer standards are those that
carry metrological information (e.g., identity or content of substance) and can be
used for the calibration of measuring instruments. RMs of various kind are used for
establishing the traceability via calibration, validation of measurement procedures,
optimization of analytical as well as being used for different levels of quality control
results (e.g., control charts, interlaboratory comparisons). Despite their wide range
of possible application, they should only be used for a single purpose in a given
measurements.
The general requirement for establishing the traceability via calibration is to ensure
that they are traceable to the SI system of units. However, in the case that certain
calibration cannot be strictly made to SI units, traceability could be established to
CRMs provided by a competent supplier in order to give a reliable physical or chemical characterization of a material or to specified method and consensus standards
that are clearly described and agreed upon by all parties concerned (as described in
Clause 6.5.3 ISO/IEC 17025:2017).
The general requirements for the reference material producers (RMP) are listed
in ISO 17034:2016, where a number of criteria for reference material (determined
uniformity, stability, the stability of certain properties, metrologically properly characterized reference value and its uncertainty) are described. In case those criteria are
fulfilled, RM may be accompanied by the certificate of RM. The necessary information, which must be indicated on the certificate of a CRM, are: the name and unique
identification of RM, the intended use, instructions for handling, period of validity
and storage conditions, property value and associated uncertainty and metrological
traceability of the certified values (as the proof of traceability).
6 Reference Materials in Chemical Measurements
much more diversed. In this case, the specific techniques used for measurement, the
complexity and diversity of test samples and often an extremely low content of the
analyte all add to the complexity of the situation, as well as necessitate the use of a
multi-step process of sample preparation.
Reference materials (RM) and certified reference materials (CRM) are an
extremely important tool for obtaining reliable results of measurements of the
chemical quantities.
6.1 Basic Definitions and Requirements
Reference material (RM) is a generic term to describe a group of materials used
as transfer standards in chemical measurements. Transfer standards are those that
carry metrological information (e.g., identity or content of substance) and can be
used for the calibration of measuring instruments. RMs of various kind are used for
establishing the traceability via calibration, validation of measurement procedures,
optimization of analytical as well as being used for different levels of quality control
results (e.g., control charts, interlaboratory comparisons). Despite their wide range
of possible application, they should only be used for a single purpose in a given
measurements.
The general requirement for establishing the traceability via calibration is to ensure
that they are traceable to the SI system of units. However, in the case that certain
calibration cannot be strictly made to SI units, traceability could be established to
CRMs provided by a competent supplier in order to give a reliable physical or chemical characterization of a material or to specified method and consensus standards
that are clearly described and agreed upon by all parties concerned (as described in
Clause 6.5.3 ISO/IEC 17025:2017).
The general requirements for the reference material producers (RMP) are listed
in ISO 17034:2016, where a number of criteria for reference material (determined
uniformity, stability, the stability of certain properties, metrologically properly characterized reference value and its uncertainty) are described. In case those criteria are
fulfilled, RM may be accompanied by the certificate of RM. The necessary information, which must be indicated on the certificate of a CRM, are: the name and unique
identification of RM, the intended use, instructions for handling, period of validity
and storage conditions, property value and associated uncertainty and metrological
traceability of the certified values (as the proof of traceability).