W
hen accurate measurement is not
possible
When accurate measurement is not possible, check the following.
Check item
Are the temperatures
of the standard
solution and sample
solution the same?
Is the stirring solution
speed appropriate?
50
Table 2 Check list
Solution
The standard solution in
calibration and the sample
solution in measurement shall
have almost the same
temperature. Match the
temperature as close as possible
by, for example, using a
thermostatic bath. The
temperature difference may
cause measurement errors.
(
"Requirements for sample
and standard solutions" (page
30))
It is best to control the stirring
speed so that the stir bar will
rotate 3 or 4 turns per second.
If swirling occurs on the surface,
the stirring speed is too fast.
Reduce the speed to a level
where swirling does not occur.
(
"Impact of stirring" (page
65))
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