Metrohm 881 Compact IC pro – Cation - Manual (Page 44)

3.13 Injection valve
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881 Compact IC pro – Cation
3.13.2 Mode of operation of the injection valve
The injection valve (see Figure 20, page 36) can adopt two valve posi-
tions - FILL and INJECT. Switching back and forth between the two valve
positions determines whether the sample path or the eluent path is gui-
ded through the sample loop. The following figure provides a schematic
display of the flow paths of the two valve positions.
1 2
4 5
3 6
1 2
4 5
3 6
1 2
4 3
5
4 3
1 2
A B
Figure 20 Injection valve – Positions
A Position FILL B Position INJECT
1 Eluent input
Capillary coming from the high pressure
pump. 2 Eluent output
Capillary to the column.
3 Sample input
Sample aspirating capillary. 4 Sample output
Capillary to waste container.
5 Sample loop
Position A In the position FILL, the sample solution flows
through the sample loop to the waste container.
The eluent flows directly to the separation col-
umn at the same time.
Position B In the position INJECT, the eluent flows through
the sample loop to the separation column. If
sample solution is to be found in the sample
loop at the time of the valve switchover, then
this will be conveyed along with the eluent, thus
making its way to the separation column. The
flow in the sample path is either stopped or the
sample flows directly to the waste container.