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DUMATHERM
Rapid nitrogen determination according to Dumas
This combustion method has already been developed at 1848 by Dumas. In
the Dumas method, a sample is burned in an oxygen rich atmosphere at
high temperatures and the resulting gases are analyzed. Now, C.
Gerhardt, being the market leader for the Kjeldahl analysis, can also
offer a highly efficient instrument with the DUMATHERM. By using the
Dumas method, this new technique offers a fast and comfortable
alternative to the classic systems. |
Control
DUMATHERM is entirely controlled via PC and the user friendly control software
Dumatherm-Manager. Since the entire analysis is controlled by software, the
amount of time that the user has to actually spend in front of the instrument,
is reduced to a minimum. Furthermore, the software includes very powerful
diagnosis and documentation functions, which facilitate an effective
interpretation of the data.
DUMATHERM PRINCIPLE
Principle of analyses
Solid or liquid samples are combusted at high temperatures in the presence of
catalysts into oxides. With the help of copper, the resulting nitrogen oxides (NOx)
are reduced to elemental nitrogen while the by-products water and carbon dioxide
are separated completely. The remaining nitrogen is analyzed using a single
filament detector.
Analysis procedure
The sample drops from the auto sampler (AS) into a purge chamber, which is
constantly purged with helium. The combustion is initiated by switching the gas
flow to oxygen and the transport into the 1000 °C hot, upright combustion
furnace (LF). The ashes are collected in a quartz tube insert, which can be
easily taken out and exchanged - even when the unit has reached operating
temperature. Among all resulting combustion products (CO2, H2O
and N-oxides), the nitrogen oxides react in the reduction furnace (RF) to
elemental nitrogen (N2). The majority of the water is separated using
an intelligent NafionŽ tube membrane system (F1), which works using a semi
permeable wall in the counter flow. Any remaining amounts are caught in an
absorption trap (F2), where the separation of CO2 is done in
self-regenerating absorption traps (F3). Elemental nitrogen remains, which is
measured in a thermal conductivity detector (TCD) without any reference gas
flow.
