Blank Values; Water Blank Values - Endress+Hauser analytikjena multi N/C UVHS Operating Manual

Function and design
Outlier selection
Average value
3.6

Blank values

3.6.1

Water blank values

Preparation water blank value
Diluent blank value
Diluent blank value use
30
The control and analysis software can automatically select outliers. The user can specify
a maximum limit for the variation coefficient or even for the standard deviation for this.
The analyzer performs the minimum number of measurements specified in the method.
If the distribution of the measured values is then above the specified maximum value
(SD or VC), additional injections are carried out from the same sample until the specified
maximum number of measurements has been reached.
After each measurement, the software determines the variation coefficient and standard
deviation for all combinations of the measured values. If the variation coefficient or the
standard deviation of at least one combination is smaller than the specified maximum
value, no further measurements are carried out.
The software determines the analysis result from the combination of measured values
with the smallest variation coefficient or the smallest standard deviation. The unused
measurements are considered outliers and deleted.
The average value of the final result is calculated from the concentrations determined
for the individual detections after eliminating the outliers.
Especially for measurements with low TOC concentrations (µg/l range), the TOC content
of the water used to prepare the standard solutions must be taken into account. The
concentration of the standard solution and the TOC blank value of the preparation water
are often within the same range. This blank value can be taken into account during cali-
bration.
The TOC content of the preparation water is measured separately before the calibration.
The software then subtracts the average integral determined for the preparation water
for each measuring point of the calibration from the determined gross integral.
I = I – I
Net Gross Preparation water
The software determines the calibration function from the net integrals. Mathemati-
cally, this corresponds to a parallel movement of the calibration line.
The software also takes the preparation water blank value into account when determin-
ing the daily factor.
If the sample is diluted, the blank value for the diluent is of interest. This value can be
determined separately or entered manually in the software. The software takes the dilu-
ent blank value into account when calculating the concentration of diluted samples.
The diluent blank value can change over time and must therefore be determined again
before beginning a measurement series. Otherwise, the software will use the last value.
The diluent blank value is always indicated in the software normalized to a volume of
1 ml.
The software calculates the actual diluent integral (I
the diluent blank value, the sample volume used and the dilution ratio. The software
then subtracts the diluent integral (I
gral (I ).
Raw
multi N/C UVHS, multi N/C pharma UV
) for each measurement based on
DiBV
) from the experimentally determined raw inte-
DiBV