7.6 Consistency Between Required Information and Supplied Information
297
case, the evaluation of this fourth step should include the systematic consideration of the
limits of detection and quantitation for the CMP concerned, as well as the highest legally
accepted level (e. g. 0,1 ng/kg), After this stricter evaluation, the immediate answer may not
be so clear and the CMP may have to be modified,
7.5.5 Implementing Corrective Actions
When the results do not meet the client's requirements or fail to reach the sought
levels in the analytical properties, the analytical approach used should be
revised following careful examination of the data provided by the quality
systems employed, which will be of great assistance in pinpointing the sources of
divergence. This may call for minimal (e.g. standards, instrumental settings),
partial (e.g. calibration system, instrument type) or global changes (e.g. methodology) in the analytical processes( es). The output of the new analytical approach
should also be subjected to the dual validation involved in the fourth step of the
analytical problem-solving process. These corrective actions are frequently
implemented with no prior planning and result in a considerable waste of time
and work.
Box 7.9
Fifth Step of the Analytical Problem-solving Process
A negative result in the evaluation of the fourth step (unvalidated results) entails the implementation of corrective actions on the analytical approach developed in the third step,
Th us, in the examples of Box 7.8, inadequate sensitivity results in uncertainty. The corrective actions to be taken involve including an analyte concentration sub-step among preliminary operations. With Cd 2 +, a chelating ion-exchange resin (e. g. Chelex 100) can be used
for this purpose; however, a larger amount of sample (e.g. scrapings of the lOy's yellow
coating) will have to be taken. Pesticides in the fruits will also call for an additional step (viz.
the solid-phase extraction of the solvent used to leach the analyte from the surface of the
pears, apples, oranges, etc).
7.6 Consistency Between Required Information
and Supplied Information
Frequently, a divorce exists between the information sought and that provided
by the laboratory as a result of the analytical problem being incorrectly planned
and solved. Figure 7.9 compares these two types of information, which can be
related in various ways as shown below.
In the ideal situation (Fig. 7.9, a), the two types of information coincide in
both qualitative (measurands, analysis types) and quantitative terms (global or
discriminate determination, uncertainty level).
Divergences between the information required and that supplied can be of
various types. Thus, the may not coincide fully (Fig. 7.9, b) owing primarily to a
297
case, the evaluation of this fourth step should include the systematic consideration of the
limits of detection and quantitation for the CMP concerned, as well as the highest legally
accepted level (e. g. 0,1 ng/kg), After this stricter evaluation, the immediate answer may not
be so clear and the CMP may have to be modified,
7.5.5 Implementing Corrective Actions
When the results do not meet the client's requirements or fail to reach the sought
levels in the analytical properties, the analytical approach used should be
revised following careful examination of the data provided by the quality
systems employed, which will be of great assistance in pinpointing the sources of
divergence. This may call for minimal (e.g. standards, instrumental settings),
partial (e.g. calibration system, instrument type) or global changes (e.g. methodology) in the analytical processes( es). The output of the new analytical approach
should also be subjected to the dual validation involved in the fourth step of the
analytical problem-solving process. These corrective actions are frequently
implemented with no prior planning and result in a considerable waste of time
and work.
Box 7.9
Fifth Step of the Analytical Problem-solving Process
A negative result in the evaluation of the fourth step (unvalidated results) entails the implementation of corrective actions on the analytical approach developed in the third step,
Th us, in the examples of Box 7.8, inadequate sensitivity results in uncertainty. The corrective actions to be taken involve including an analyte concentration sub-step among preliminary operations. With Cd 2 +, a chelating ion-exchange resin (e. g. Chelex 100) can be used
for this purpose; however, a larger amount of sample (e.g. scrapings of the lOy's yellow
coating) will have to be taken. Pesticides in the fruits will also call for an additional step (viz.
the solid-phase extraction of the solvent used to leach the analyte from the surface of the
pears, apples, oranges, etc).
7.6 Consistency Between Required Information
and Supplied Information
Frequently, a divorce exists between the information sought and that provided
by the laboratory as a result of the analytical problem being incorrectly planned
and solved. Figure 7.9 compares these two types of information, which can be
related in various ways as shown below.
In the ideal situation (Fig. 7.9, a), the two types of information coincide in
both qualitative (measurands, analysis types) and quantitative terms (global or
discriminate determination, uncertainty level).
Divergences between the information required and that supplied can be of
various types. Thus, the may not coincide fully (Fig. 7.9, b) owing primarily to a