XIV
The
Spectroquant
®
PipeCheck
is used
to check the pipettes. The pack contains
cells filled with colour-dye concentrates.
After the addition of a predefined volume
of water using the pipette in question, the
cell is measured against a corresponding
reference cell also contained in the pack.
The difference in the absorbance values
of the measurement cell and reference cell may not
exceed the tolerances given in the package insert.
If the tolerances are exceeded, the instructions given
in the section “Pipetting system” must be followed
accordingly.
5. Analytical Quality Assurance (AQA)
5.2.3 Checking the Pipettes
The thermoreactors are
checked at 100 /120 and
148 °C. Here a round cell
filled to one half with gly-
cerol is place in any one
of the compartments of
the thermoreactor, and
the thermoreactor is
heated as described in
the instructions for use. After the control lamp has
gone out, the temperature in the cell is measured
using a calibrated thermometer. The following
desired temperatures must be achieved:
Block temperature 100 °C = desired temp. 100 ±3°C*
Block temperature 120 °C = desired temp. 120 ±3°C*
Block temperature 148 °C = desired temp. 148 ±3°C*
5.2.4 Checking Thermoreactors
* The block temperature compensates for any heat lost due to insufficient heat transfer.
The user’s own mode of opera-
tion must also be subjected to an
exact analysis. The following
questions may serve as a guide in
this regard:
●
Is the test kit optimal for the
measurement assignment in
question?
●
Is the test kit’s measuring
range suitable?
●
Were the operating instructions for the test
followed?
●
Was the sample volume correct?
●
Was the pipette handled properly?
●
Was a new pipette tip used?
●
Is the pH correct?
●
Was the reaction time adhered to?
●
Does the sample and reagent temperature lie
within the correct range?
●
Is the cell clean?
●
Has the expiry date for the test kit been exceeded?
The influence of other substances contained in the
sample may, under certain circumstances, be so
great that their recovery rates lie in the region of
several percent. It is recommended to check for any
influence by using the addition solution contained in
the Spectroquant
®
CombiCheck pack.
A defined quantity of the
addition solution
(R-2),
which contains a known concentration of the respec-
tive analyte, is added to the sample and the recovery
rate is determined.
The following difference is then calculated:
Result ( addition solution) – Result (sample)
If the calculated difference is equal to the concen-
tration of analyte of addition solution that was added,
the recovery rate is 100 %. If the difference is less
than 90 %, then a matrix interference is present.
5.2.5 Testing for Handling Errors
5.3 Determination of Sample Influences
Carefully
pipette 3 ml of
the sample into a reaction
cell, close tightly with the
screw cap and mix
vigorously.
Caution, the
cell becomes very hot!
Release 07/03
