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Sum parameters – Total Organic Carbon
TOC – Control samples and control cards
SCA-130-516
Analytical quality assurance is an important Users can define their own parameters for
topic in many analytical application areas. each control sample. The results can be
Various information leaflets as well as specified either in terms of concentration or
appropriate quality standards provide tips or directly in terms of recovery.
guidelines on the most suitable measures to Blind value controls can be defined as well.
attain high-level analytical quality. The blind values are usually entered without
specifying a concentration (area).
■ Control samples
Control samples are important tools in ■ Measures
analytical quality control. Specially prepared The TOC autosamplers often run overnight
solutions of known concentration are used to and process the samples sequentially until
test the system and the validity of the specific the next morning. All the more annoying
calibration. The control samples are treated when the analytical staff finds out the
like unknown samples to determine the following morning that the control samples
concentrations or recovery. The user’s quality are outside of the specified tolerance limit. In
management system specifies a tolerance such cases, the software offers a solution.
range the target value should be in.
When tolerance limits are exceeded, the
The TOC Control software of the TOC-L and software can, for example, start an automatic
TOC-V systems enable the definition of such recalibration or repeat the run of the last
control samples. control sample within the tolerance limits.
When ‘precious’ samples need to be
measured, or only very small amounts of the
sample material are available, the analytical
run can also be stopped.
■ Control cards
In order to identify trends or system
deterioration in due time, the measurement
values of the control samples are
documented on a time axis. This leads to so-
called control cards, in which the results are
listed on the Y-axis and the corresponding
Figure: Control sample parameters. dates on the X-axis.
