Metrohm 761 Compact IC - Manual (Page 179)

5.1 Practical notes on ion chromatography
761 Compact IC
169
5 Notes – Maintenance – Faults
5.1 Practical notes on ion chromatography
5.1.1 Separating columns
Separation efficiency
The attainable quality of analyses with the 761 Compact IC depends to
a large extent on the separation efficiency of the column used. When
purchasing an IC column you should ensure that the separation effi-
ciency suffices for the analysis problems at hand. Ascertain the charac-
teristic data of the IC column on the standard chromatogram en-
closed with the column such as capacity factors, selectivity, plate
number and resolution and check these data with your own measure-
ments. If any difficulties arise, you should always first check the quality
of the column by recording a standard chromatogram.
You will find additional general tips on handling IC separating columns
in the 8.732.2003 Metrohm Monograph "Ion chromatography", as
well as detailed information on the separating columns available from
Metrohm (see section 6.3.2) in the leaflets supplied and in the special
Application Bulletins available free of charge from your nearest
Metrohm agency.
Protection
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 high-pressure pump, it is advantageous to install an in-line filter
between the pump and the injection valve. In the 761 Compact IC a
6.2821.120 Filter unit PEEK is already mounted for this purpose (see
section 2.6.2).
The use of readily interchangeable precolumns serves to protect the
actual separating columns and increase their service life appreciably.
The precolumns available from Metrohm (see section 6.3.2) are either
actual precolumns or so-called precolumn cartridges which are used
together with the 6.2821.040 Cartridge head or the 6.2828.010 Precol-
umn cartridge holder (see section 2.7).