Metrohm 872 Extension Module IC Pump - Manual (Page 48)

6.4 High pressure pump
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872 Extension Module IC Pump
pH pH changes result in shifts in the dissociation
equilibria and hence changes in the retention
times.
Organic solvents The addition of an organic solvent (e.g. metha-
nol, acetone, acetonitrile) to aqueous eluents
generally accelerates lipophilic ions.
6.3.2 Operation
6.3.2.1 Supply bottle
The supply bottle with the eluent must be connected as indicated in Chap-
ter 4.4.1, Page 24. This is above all important for eluents with volatile sol-
vents (e.g. acetone).
Moreover, condensation must also be prevented in the eluent bottle. Drop
formation can change the concentration ratio in the eluent.
6.3.2.2 Aspiration filter
To protect the IC system against foreign particles, we recommend aspirat-
ing the eluents via a 6.2821.090 aspiration filter (15-2). This aspiration fil-
ter must be replaced should it show signs of yellow discoloration (but no
later than every 3 months).
In the case of very sensitive measurements, the eluent should be stirred
constantly with a magnetic stirrer.
6.3.2.3 Changing the eluent
When changing the eluent, it must be ensured that no precipitates can
occur. Solutions following one another in direct succession must therefore
be miscible. If the system has to be rinsed organically, several solvents
with rising or falling lipophilia must be used.
6.4 High pressure pump
6.4.1 Protection
Caution
The pump head is filled ex works with methanol/ultra pure water. It
must be ensured that the eluent used is freely miscible with the solvent
remaining in the pump head.
To protect the high pressure pump against foreign particles, we recom-
mend that the eluent undergoes a microfiltration (filter 0.45 µm) before
being aspirated via a 6.2821.090 aspiration filter (see "Assembling eluent
aspiration tubing", page 25).