Metrohm 818 IC Pump - Manual (Page 29)

4.1 Practical notes
818 IC Pump / 8.818.1023 Instructions for Use
23
4 Notes – Maintenance – Faults
4.1 Practical notes
4.1.1 Protection against foreign particles
To protect the column against foreign particles which could have an
adverse influence on the separation efficiency, we advise you to subject
both the eluents and all samples to microfiltration (0.45 µ m filter) and
to siphon the eluent through the 6.2821.090 Aspirating filter.
To avoid contamination by abrasive particles arising from piston seals
of the 818 IC Pump, it is advantageous to install an in-line filter 24
between the pump and the 820 IC Separation Center (see Fig. 5). We
recommend to use the 6.2821.100 Filter unit PEEK which is included
in the standard accessories of the 818 IC Pump (see section 2.3.3).
4.1.2 Pulsation dampener
To protect the column material against pressure shocks caused by
injection we recommend to use a pulsation dampener between the 818
IC Pump and the 820 IC Separation Center (see Fig. 5). The optional
6.2620.150 Pulsation dampener MF (see section 2.3.2) is eminently
suitable for this purpose.
4.1.3 Eluents
Treatment
For the preparation of the eluents one should use chemicals of a purity
degree of at least "p.a.". For dilution please use only high purity water.
Fresh eluents should always be microfiltered (0.45
µ m filter) and
degassed (with N
2
, He or vacuum). For in-line degassing of eluents the
837 IC Eluent Degasser is available from Metrohm. The eluent should
be continuously stirred with a magnetic stirrer, particularly when the
recycling procedure is employed or when alkaline eluents are used. For
alkaline eluents and eluents with low buffering capacity one should
preferably use CO
2
absorbers.
The supply vessel containing the eluent must be closed as tightly as
possible to avoid excessive evaporation. This is primarily important with
eluents containing organic solvents (e.g. acetone), the evaporation of
which can lead to drifts in the long term. If work is performed in a very
sensitive range, even if one drop of condensate falls back in the eluent
this can cause a noticeable change in the background conductivity.
Precipitates
Salt crystals between the piston and the seal are the cause of abrasive
particles, which can enter the eluent. These lead to contaminated