Metrohm 850 Professional IC Anion MSM-HC - Gradient - Manual (Page 75)

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5 Operation and maintenance
850 Professional IC Anion MSM-HC HP-Gradient
￭￭￭￭￭￭￭￭ 65
5.4.2.3 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.
5.5 High pressure pump
5.5.1 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 28).
Salt crystals between the piston and seal cause abrasion particles which
can find their way into the eluent. These lead to contaminated valves, a
rise in pressure and in extreme cases scratched pistons. It is therefore
essential to ensure that no precipitates can occur (see Chapter 5.4.2.3,
page 65).
Caution
In order to spare the pump seals, the pump should not be operated dry.
Therefore ensure that the eluent supply is correctly connected and that
there is enough eluent in the eluent bottle each time before turning on
the pump.
5.5.2 Maintenance
Caution
Maintenance work on the high pressure pump may not be carried out
unless the instrument is switched off.