Buchi DuMaster D-480, Руководство по эксплуатации

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Operating instructions DuMaster D-480 ©BÜCHI Labortechnik AG
7 - Using the instrument 141

The Ash crucible / ash finger.

The Regainer.

The Reductor.

Is the detector signal small and stable?

Is the proper method allocated to the respective samples?

Is the carousel loaded?
If you answer yes to all of the above, you can start measuring real samples.
Types of blank value determination and their settings
Background
Blank value determination can be used for various purposes and is therefore performed in different
ways. The different types of blank value determination are described below with an explanation of the
respective settings.
Degree of gas tightness (N blank value)
This blank value determination is performed as a routine task. It makes sense after gas cylinder
replacement and after maintenance work.

The blank value determination is performed without a sample.

Use the method "Blank with O2".

The N integral values should be between 10 and 50 after stabilization. If your N integral values
are significantly higher than 50, repeat the blank value determination with methods which is
associated with an oxygen dosing time. If the N integral values are then normal, the oxygen was
contaminated. Otherwise, the system has probably a leak.
Sample additives or packing material
Blank samples are measured for blank value determination of sample additives (e.g. WO
3
powder) or
packing material:

prepare blank samples:

without sample substance

with equal amount of sample additives

with the same packing material and the same packing method.

For the blank sample, use the same method used for the real sample.

The mean value of the blank value integrals is then entered in the software and deducted from
the samples.

Only if the blank value always remains the same by preparing the sample accordingly, it can also
be "calibrated" and does not have to be deducted. However, in this case standard substances
must be prepared in the same way as the samples for calibration and daily factors.
Determining blank values
Condition
The name of the blank sample must be defined in
Options > Settings > Keywords
. Ex works, "Blnk"
is already defined as the key word of the blank sample. If you want to change this, you must define
the new name via
Options > Settings > Keywords
.