19
HTEC-500
10-2. Identification of Precolumn Quality
If the shape of the chromatogram becomes asymmetric, repacking of the precolumn may be required.
This is especially true if the latter half of the peak gets dull (tailing) or if the top of the peak is divided into
two small peaks.
To check if the precolumn needs to be repacked, read the following:
• Inject a standard sample and confirm that the shape of the peak is asymmetric. If the shape is
normal, then there must be another cause. See Troubleshooting.
• Disconnect the precolumn and replace it with a two-way joint. Then inject a standard sample and
check the shape of the peak. If it is symmetric when the sample is loaded directly onto the column
without a precolumn, it indictates that the precolumn must be repacked. If not, the separation
column may be damaged.
Blocking of the precolumn filter raises the outlet pressure of the pump. If the precolumn generates more
than 2 MPa (please compare with and without precolumn), the upstream filter must be exchanged and
the precolumn must be repacked. Repacking of a precolumn requires the precolumn packing tool set.
Select the precolumn packing material according to Eicom technical notes. See also Table 3.
If Using the PP-ODS Column
It is difficult to know if the precolumn should be repacked because the sample is not introduced into
the precolumn in the case of microdialysis. For this reason, repack it every two or three months. Blocking
of the precolumn filter raises the outlet pressure of the pump. If this pressure rises more than 1.5 MPa
more than usual, the upstream filter must be exchanged and the precolumn must be repacked.
Table 3. Precolumn packing material
Separation column
Columns for microdialysis
AC-GEL
CA-5ODS
E-GEL
SC-3ODS, SC-5ODS
Pre-column packing material
Any packing material can be applied. (AC-ODS is the
cheapest.) Set it upstream of the injector.
CH-GEL
CA-ODS
CH-GEL
AC-ODS
CA-ODS (for mobile phase whose pH is around 6)
