96
7 Validation of the Measurement Procedure
7.8 Validation of Measurement Procedure
Analysts are primarily interested in real samples, whose qualitative and quantitative
composition is very complex, and what is more—unknown. Thus, the evaluation
of the measuring procedure cannot be limited only to the measuring technique, but
should cover all stages, including the collection and preparation of samples. The
analyst is not only responsible for the correct implementation of a given measurement
technique for determining the content of a substance in a complex object, but should
also understand the problem of a customer and be aware on how the results will be
used—this will involve the proper definition of the measurand. As a result, more
and more attention is paid to all stages of the measurement process and their impact
on the final result. This is related to an in-depth understanding of the variability of
chemical equilibria and the changes the analyzed objects undergo within the storage
and preparation process.
Validation of the measurement procedure is considered to be one of the most
important responsibilities of the laboratory. When selecting an appropriate analytical
method, the laboratory should take into account their experience and the capabilities
of their infrastructure, above all else; the laboratory should also consider the time and
cost of analysis. Validation of the selected procedure allows the customer to evaluate
relevant evidence documenting the analytical parameters of the proposed procedure.
The scheme of the validation process:
– To identify all requirements for the intended use of the results;
– To determine essential analytical parameters of the proposed measurement procedure;
– To compare the obtained parameters with the requirements;
– To confirm that the selected measuring procedure meets the predetermined requirements.
In this aspect, the analytical process is multifacted, and the most important aspects
may include sampling a representative portion of the test object; the preparation
of an appropriate number of analytical sub-samples, so that it is possible to make
repetitive measurements; the preparation of laboratory samples for testing (which
includes dissolution, digestion, extraction, concentration, dilution, separation, etc.);
calibration of the measuring instrument; monitoring the reliability of the results; and
the evaluation of the results obtained.
As validation requires confirmation that the specific requirements were met for the
specific intended use, the most essential part is the assessment of the analytical performance of the measurement procedure and the evaluation of selected features of the
result. The parameters characterizing the measurement procedure are measurement
range, linearity, sensitivity, limits of detection and quantitation. Moreover, there are
parameters that characterize the result of the determination—namely, measurement
traceability and uncertainty of the results (Table 7.3).
The laboratory may use the various tools enabling validation, those described
in the relevant standards or by the authorized institutions. In the case of reference
7 Validation of the Measurement Procedure
7.8 Validation of Measurement Procedure
Analysts are primarily interested in real samples, whose qualitative and quantitative
composition is very complex, and what is more—unknown. Thus, the evaluation
of the measuring procedure cannot be limited only to the measuring technique, but
should cover all stages, including the collection and preparation of samples. The
analyst is not only responsible for the correct implementation of a given measurement
technique for determining the content of a substance in a complex object, but should
also understand the problem of a customer and be aware on how the results will be
used—this will involve the proper definition of the measurand. As a result, more
and more attention is paid to all stages of the measurement process and their impact
on the final result. This is related to an in-depth understanding of the variability of
chemical equilibria and the changes the analyzed objects undergo within the storage
and preparation process.
Validation of the measurement procedure is considered to be one of the most
important responsibilities of the laboratory. When selecting an appropriate analytical
method, the laboratory should take into account their experience and the capabilities
of their infrastructure, above all else; the laboratory should also consider the time and
cost of analysis. Validation of the selected procedure allows the customer to evaluate
relevant evidence documenting the analytical parameters of the proposed procedure.
The scheme of the validation process:
– To identify all requirements for the intended use of the results;
– To determine essential analytical parameters of the proposed measurement procedure;
– To compare the obtained parameters with the requirements;
– To confirm that the selected measuring procedure meets the predetermined requirements.
In this aspect, the analytical process is multifacted, and the most important aspects
may include sampling a representative portion of the test object; the preparation
of an appropriate number of analytical sub-samples, so that it is possible to make
repetitive measurements; the preparation of laboratory samples for testing (which
includes dissolution, digestion, extraction, concentration, dilution, separation, etc.);
calibration of the measuring instrument; monitoring the reliability of the results; and
the evaluation of the results obtained.
As validation requires confirmation that the specific requirements were met for the
specific intended use, the most essential part is the assessment of the analytical performance of the measurement procedure and the evaluation of selected features of the
result. The parameters characterizing the measurement procedure are measurement
range, linearity, sensitivity, limits of detection and quantitation. Moreover, there are
parameters that characterize the result of the determination—namely, measurement
traceability and uncertainty of the results (Table 7.3).
The laboratory may use the various tools enabling validation, those described
in the relevant standards or by the authorized institutions. In the case of reference