How it works, Figure 1, Dual suppressor flow diagram – Metrohm 828 IC Dual Suppressor User Manual
Page 10: 2 how it works, 1 introduction, Resin-so, Oor nahco, Sample: mx + resin-so, Hx x = cl
1 Introduction
828 IC Dual Suppressor/ 8.828.1003 Instructions for Use
2
1.2 How it works
The
828 IC Dual Suppressor is used to increase the sensitivity of the
detection of anions in conductivity measurements. It is installed
between the separation column and the conductivity detector. The IC
Dual Suppressor consists of a suppressor cell, a direct current source
and a degassing unit. After it enters the suppressor cell the eluent
containing the sample ions is split proportionally toward the detector,
anode and cathode as shown in Figure 1.
Figure 1:
Dual suppressor flow diagram
Three processes take place simultaneously in the 828 IC Dual
Suppressor:
1. As the eluent and the sample ions emerge from the separation
column an acid/base reaction converts them to their protonated
forms. The cell is packed with a strong cation exchanger which is
present in protonated form. The following exchange reactions occur
in the suppressor:
Eluent:
NaOH + Resin-SO
3
-
H
+
Resin-SO
3
-
Na
+
+ H
2
O
or
NaHCO
3
/Na
2
CO
3
+ Resin-SO
3
-
H
+
Resin-SO
3
-
Na
+
+ H
2
CO
3
Sample:
MX + Resin-SO
3
-
H
+
Resin-SO
3
-
M
+
+ HX
X = Cl
-
, NO
3
-
, Br
-
, etc.
2 H
2
O 4 H
+
+ O
2
+ 4 e
-
NaOH + MOH + H
2
+ NaX
Degassing Unit
H
2
CO
3
CO
2
+ H
2
O
H
2
O + HX
To Detector
H
2
CO
3
+ HX
NaHCO
3
/Na
2
CO
3
+ MX
2 H
2
CO
3
+ O
2
+ HX
M = Cations (Na
+
, K
+
, Mg
2+
, etc.)
X = Anions
+
H
+
H
+
H
+
H
+
2 H
2
O + 2 e
-
H
2
+2 OH
-
Anode
Cathode
OUT
IN
H
+
form Resin
Na
+
form
Resin