Function and design
multi N/C pharma HT
34
The following equation applies for the linear calibration function:
c = (k
1
x I
eff
+ k
0
)/V
Sample
x N
D
/N
P
If the user dilutes a sample and enters the dilution ratio in the software, the software
automatically calculates the concentration of the undiluted primary sample and outputs
it to the analysis report.
3.7.2
Eluate blank value
The eluate blank value is a special blank value for samples from cleaning validation or
eluate preparation. It corresponds to the TOC content of the ultrapure water used which
has been used, e.g., to extract/eluate swabs.
The eluate blank value is a fixed method parameter. The user can activate or deactivate
the eluate blank value in the method. The user can optionally determine the eluate
blank value separately and enter it in the software manually.
The blank value can change over time and must therefore be determined again before
beginning a measurement series. Otherwise, the software uses the last value.
The eluate blank value is always indicated normalized to 1 ml.
The eluate blank value is not taken into account when carrying out a calibration. The
calibration is carried out with normal standard solutions in which only the preparation
water blank value is taken into account.
If samples are measured with the so-called eluate method, the software automatically
subtracts the integral of the blank value from the integral of the sample measurement.
I
eff
= I
Raw
– I
Eluate blank value
I
eff
: Effective integral
I
Raw
: Raw integral
I
Eluate blank value
: Eluate blank value
3.7.3
Boat blank value
For solids methods, the user can determine the boat blank value. To do this, the user in-
serts a boat with sample additives in the combustion furnace and analyzes it.
The user can optionally determine the boat blank value separately and enter it in the
control and analysis software.
The boat blank value can change over time and must therefore be determined again be-
fore beginning a measurement series. Otherwise, the software will use the last value.
3.8
System suitability test
System suitability tests are used in the pharmaceuticals industry to validate analytical
methods and devices to document the suitability of the selected procedure.
For TOC analysis in the ultrapure water range for pharmaceutical purposes, such as e.g.,
WFI (Water For Injection), the recovery rate of a poorly oxidizable compound is deter-
mined in comparison with that of an easily oxidizable compound.
The standards solutions and their concentrations are defined in the respective pharma-
copeia, e.g., in the European Pharmacopeia or in the USP (United States Pharmacopeia).
These define sucrose as an easily oxidizable compound, and p-benzoquinone as a poorly
