multi EA 5000
Function and design
17
Sample feed
Liquid/LPG/gaseous
Sample feed
Solid/liquid/LPG/gaseous
Cl analysis - (EOX/TOX/AOX)
C/N/S analysis
C detector
N detector
S detector
Coulometer
Dryer
Flame sensor
Quartz glass boat
Cooled sample port
Figure 1 Operating modes of the multi EA 5000
4.1.1.2 Sample Digestion
TS, TN, TC, TX and EOX
Sample digestion to determine TS, TN, TC, TX and EOX can be performed in vertical and
horizontal operation mode.
Digestion is a two-stage process at 1000 to 1100 °C via pyrolysis with subsequent ther-
mal oxidation. In the first phase, the sample components are pyrolyzed in an argon flow,
and the generated pyrolysis gases are incinerated in an oxygen flow. Next, the remain-
ing pyrolysis products are re-incinerated in a pure oxygen flow during the second phase.
This digestion is summed up via the following equations:
R*-H + O
2
→ CO
2
+ H
2
O
R*-N + O
2
→ NO
x
+ CO
2
+ H
2
O
R*-S + O
2
→ SO
2
+ CO
2
+ H
2
O
R*-X** + O
2
→ HX** + CO
2
+ H
2
O
R* - carbonic substance
X** - F
-
, Cl
-
, Br
-
, I
-
TOC
Digestion for TOC determination is performed in vertical operation mode via thermal ox-
idation in an oxygen flow at 700 °C. The aqueous samples are injected directly into the
TOC combustion tube via the injection port.
TIC
Digestion for TIC determination is performed in the TOC module via wet chemical oxida-
tion with phosphoric acid. The aqueous samples are injected into the TIC reactor manu-
ally.
AOX
Digestion for AOX determination is performed in the horizontal operation mode. The
loaded active carbon is combusted in the oxygen flow at at least 950 °C and forms hy-
drogen halogen, carbon dioxide and water. The loaded active carbon is transferred to
the multi-purpose combustion tube with or without a quartz container in the quartz
glass boat with ABD.
