Measurements
21
Spectrophotometer
NANOCOLOR
®
Advance 1.0, 11.2020
The “Correction measurement” option can be used, if a correction
value
(see 11.4 Determination of corrections values, page 21)
is applied to compensate for a measurement error with colored or
turbid samples.
With the command
Do not save
, the measurement result is not
stored in the instrument memory when the cuvette is removed or
when the menu is exited.
NOTICE
The
Do not save
function is only available in
Open Mode
.
11.4 Determination of corrections values
These instructions are only to be used in connection with the
original instructions of the
NANOCOLOR
®
cuvette tests. The
photometric analysis of water samples with inherent color or tur-
bidity requires the determination of a correction value. Colors and
turbidity influence the measurement and therefore lead to devi-
ating measured values. The correction values require a special
procedure for each test. For example, it is not always sufficient
to measure the intrinsic color of the sample without reagents and
subtract it from the measured value. In many cases the reagents
change the intrinsic color or turbidity of the sample. All changes to
the sample, such as dilution, addition of chemicals that influence
pH or redox potential, must be reproduced as in the original anal-
ysis. Only the coloring reagent is not added.
In the
NANOCOLOR
®
Advance spectrophotometer, the correc-
tion value program is activated after the normal evaluation (value
A) by selecting the “correction value” entry via the
icon in the
result window
(see 11.3 Result view, page 19)
.For this purpose,
the cuvette with the correction value (value B) is requested and
measured. The corrected measurement result is displayed and
stored. Depending on the test, the photometer requires a zero
measurement for the correction value in addition to the correction
value cuvette.
Underlying procedure:
measured value according to original instruction = A
correction value according to special specification = B Analysis
value = A – B
Exceptions: Methods in which decreasing absorbance is mea-
sured against a reagent blank value. Then the following applies:
Analysis value = A + B. This is pointed out in the corresponding
tests.
It is very important that only values of the same dimension are
subtracted from each other (e.g. mg/L N; mg/L NH₄; mmol/m³;
Abs).
