500 D 01/2012
24a
3.5.7 Dilution of samples
In analytical practice it is often necessary to dilute a sample, until the concentration
to be determined is within the measuring range.
Example:
expected measurement value: between 80 and 200 mg/L
range of photometric test:
0.1–10.0 mg/L
required dilution
(200
→
10 mg/L): at least 1 : 20
recommended dilution:
1 : 25 or even 1 : 50 in order to obtain a result
in the middle of the measuring range
Input of a dilution is as 1 part sample plus x parts dist. water, in order to obtain
unambiguous identification of small dilutions, too. It is possible to enter dilutions
from 1 + 1 to 1 + 999.
Before you remove the cuvette from the cuvette slot, press key
F3
and enter the
dilution. After input the dilution is displayed in the lower status line together with
all other parameters of the current data set, and the resulting measuring value is
directly calculated and displayed. When you remove the cuvette, the complete data
set is stored.
1671 NITRITE
1234 sewage A
1+0
dilution:
1 +_
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1671 NITRITE
1234 sewage A
1+0
dilution:
1 +24_
17.11.11 16:06
Please note: any entered dilution only concerns the current measurement. For very
large dilutions, e.g. 1 + 999, the result may be displayed in a different dimension in
order to be presentable.
3.5.8 Automatic determination of a correction value
Turbid or colored samples require preparation of a correction value. After normal
evaluation (with coloration/turbidity) measurement of the correction value is activat
-
ed by pressing
OK
. The programme asks for a cuvette with the correction value (see
chapter 5.11), which is then measured. The corrected measuring result is displayed
and stored, when the cuvette is removed.
1671 NITRITE
0001 place
1+0
Zero c val
→
Z
17.11.11 16:06
