Changing The Eluent; Notes On Operating The High-Pressure Pump - Metrohm 883 Basic IC plus Manual

￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
4.4.2

Changing the eluent

4.5

Notes on operating the high-pressure pump

883 Basic IC plus
The composition of the eluent plays a critical role in chromatographic ana-
lysis:
Concentration
pH
Organic solvents
Ensure that no precipitates can form when changing the eluent. Immedi-
ately successive solutions must be miscible. If the system must be rinsed
with organic solvents, several solvents with rising or falling lipophilicity
must be used.
NOTICE
To change the eluent, remove the guard column and the separation col-
umn. Connect the capillaries using a coupling (6.2744.040) and two
pressure screws (6.2744.070).
CAUTION
The pump head is filled ex works with methanol/ultrapure water. Ensure
that the eluent used is miscible with this solvent.
Keep the following recommendations in mind in order to protect the high-
pressure pump from damage as much as possible during operation:
To protect the high-pressure pump from foreign particles, we recom-
￭
mend filtering the eluent through a filter with a pore size of 0.45 µm
and aspirating it via an aspiration filter (6.2821.090).
An increase in the concentration generally leads
to shorter retention times and faster separation,
but also to a higher background conductivity sig-
nal.
pH changes lead to shifts in dissociation equili-
bria and thus to changes in retention times.
Adding organic solvents (e.g. methanol, acetone
or acetonitrile) to a watery eluent generally
speeds up lipophilic ions.
4 Operation and maintenance
￭￭￭￭￭￭￭￭
59