Checking The Photometer; Checking The Overall System - wtw PhotoLab S6 Operating Instructions Manual

5. Analytical Quality Assurance (AQA)

5.2.1 Checking the Photometer

As soon as the photometer is activated it is running a
Self-Check. This means the hardware and the soft-
ware of the photometer is checked and compared
with internal standards.
445, 525, and 690 nm wavelengths. The test solutions
are measured in a reference photometer monitored
with primary standards, and the absorbance values
are documented in the package insert. These desired
values with the permissible tolerances are entered
into the photometer or else handwritten into the con-
trol chart. For the measurement the cell is placed in
the compartment for the round cell and identified by

5.2.2 Checking the Overall System

Test for the overall system includes checking the
working equipment and checking the handling
operations.
The overall system can be checked using standard
solutions of a known content, preferably with the
®
Spectroquant CombiCheck; this corresponds with
the AQA 2 mode in the photometer.
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Spectroquant CombiCheck are ready-to-use
standard solutions that in terms of the analyte
concentration are finely adjusted to the individual
test kits. They contain a mixture of several analytes
that do not interfere with each other. The standard
solution (R -1) is used in the same way as a sample.
A double determination is recommended as a
measure to diagnose any random errors.
The desired values with the permissible tolerances
are already electronically stored with the method in
the photometer. The AQA check mode is selected for
the measurement, which can be prompted using the
MemoChip AQA. The cells containing the standard
solution are then identified as test solutions by the
photometer, and the measured concentration is then
compared with the desired value. When the result
agrees with desired value within the permissible tole-
rance range, the display shows the measurement
value and the "OK" sign.
Release 07/03
The photometer itself is
checked in the AQA 1
mode using the Spec-
®
troquant PhotoCheck.
The pack includes round
cells containing stable
test solutions (secondary
standards) for checking
the photometer at the
the photometer via the bar code, and the measured
absorbance is compared with the desired value.
The absorbance is shown in the display and can be
entered into the corresponding control chart.
The measurement of at least one cell (preferably cell
-2 or -3) per wavelength is recommended when
checking the photometer. The measurement of four
cells for a given wavelength tests – in addition to the
wavelength accuracy – also the linearity of the absor-
bance over the effective range.
The verification of the instrument, as it is required by
DIN/ISO 9000 or GLP, can be easily performed by
using the PhotoCheck. The PhotoCheck allows you
to check the linearity of the filters, hence offering the
possibility to check the instrument. All of the corres-
ponding documentation, required by these certifi-
cation guidelines, is done by the photometer auto-
matically. We guarantee for the Spectroquant
PhotoCheck a 2 year warrantee.
In addition to the CombiCheck, it is also possible to
use ready-to-use single-element standard solutions
for this checking procedure. These contain 1000 mg
of the respective analyte per liter of solution. They
can be diluted to different final concentrations, which
should preferably lie approximately in the middle of
the measuring range of the respective test kit.
The table on page XVIII provides an overview of the
available CombiCheck and ready-to-use standard
solutions.
Due to limited shelf-life characteristics, there are no
CombiCheck or ready-to-use standard solutions
for certain parameters. Attached to the table are the
instructions describing the reagents and working
steps necessary to make your own solutions of a
defined concentration. This allows the control of
parameters where there are no simple to prepare
solutions available.
The individual results are flagged as AQA2 if the
AQA-Check of the entire system has passed. If not,
an error message is given and the individual compo-
nents of the instrument have to be checked in detail.
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