4
–
Example Applications
Thermo Scientific
Product Manual for IonPac AS31 Columns
Page 28 of 45
155007-01
For Research Use Only. Not for use in diagnostic procedures.
The suppressor eluent out is connected to the conductivity cell inlet. The cell outlet is connected to a 6-port valve that
is used for matrix diversion.
Figure 10 Connections from Ion Chromatograph to Mass Spectrometer through a
Matrix Diversion Valve
Figure 10 shows the connections for the matrix diversion valve. During target analyte elution, the 6-port valve is set to
position A, where flow from the conductivity cell is directed to the Mass Spectrometer for gas-phase ionization and
analysis. When matrix ions such as sulfate, chloride, nitrate, and carbonate elute, the valve is switched to position B to
direct the flow from the cell outlet to the suppressor for “recycle mode”. Matrix diversion is necessary to prevent
contamination of the mass spectrometer with matrix ions (present at high concentration in some samples). Poor
sensitivity and poor recovery (ion-suppression in the mass spectrometer) may result if sample matrix ions present at
ppm (mg/L) levels are not diverted to waste. The mass spectrometer source may occasionally require physical cleaning
followed by several hours of vacuum pumping to regain pristine performance. Note that the IC eluent line should not
be connected to the MS inlet until the background conductivity is below ~3 µS.
If an ICS-5000
+
or ICS-6000 is used, any of the 6 or 10-port valves in the automation
manager (AM) module can be used for matrix diversion.
Makeup DI water can be added to the analytical flow during matrix diversion to keep the system equilibrated. If an
ICS-5000
+
with a DP pump module is used, the second pump can be used to provide the makeup flow. Otherwise, a
second (auxiliary) pump is used for this purpose. A Dionex AXP (Item # 063973) auxiliary pump was used in this
example. The flow of makeup solvent is 0.3 mL/min in the IC/MS example above. To avoid tubing constriction at
connections and its potential for causing elevated pressures, we employed 0.005” ID Viper® tubing for IC/MS
operation.
Grounding Connection: A grounding adaptor is needed when the liquid line connection
from the IC is made directly to the mass spectrometer electrospray probe. However, if the
connection is made through a grounded adapter present on the MS, there is no need for
another ground.
1
2
3
4
5
6
To
Suppressor
R
EGEN IN
From
Auxiliary
Pump
To Mass
Spectrometer
From
Conductivity
Cell Outlet
Loop
Position A
Position B
NOTE
!
NOTE
!
