IonPacAS9-SC
034656-06
Page 27 of 28
6.3
Loss of Front End Resolution
If poor resolution or efficiency is observed for the peaks eluting near the system void volume compared to the later eluting peaks,
check the following:
A. Improper eluent concentration may be the problem. Remake the eluent as required for your application. Ensure that
the water and chemicals used are of the required purity.
B. Column overloading may be the problem. Reduce the amount of sample ions being injected onto the analytical column
by either diluting the sample or injecting a smaller volume onto the column.
C. Sluggish operation of the injection valve may be the problem. Check the air pressure and make sure there are no gas
leaks or partially plugged port faces. Refer to the valve manual for instructions.
D. Improperly swept out volumes anywhere in the system prior to the guard and analytical columns may be the problem.
Swap components, one at a time, in the system prior to the analytical column and test for front-end resolution after
every system change.
6.4
Poor Peak Resolution
Poor peak resolution can be due any or all of the following factors.
6.4.1 Loss of Column Efficiency
A. Extra-column effects can result in sample band dispersion, making the peaks' elution less efficient. Make sure you are
using PEEK tubing with an ID of no greater than 0.010" to make all eluent liquid line connections between the injection
valve and the detector cell inlet, and that the tubing lengths are as short as possible. Check for leaks.
B. Check to see if headspace has developed in the guard or analytical column (e.g., due to improper use of the column
such as submitting it to high pressures). Remove the column’s top end fitting (see Section 5.1.2, Replacing Column
Bed Support Assemblies). If the resin does not fill the column body all the way to the top, it means that the resin bed
has collapsed, creating a headspace. The column must be replaced.
6.4.2 Poor Resolution Due to Shortened Retention Times
Even with adequate system and column efficiency, resolution of peaks will be compromised if analytes elute too fast.
A. Ensure that the eluent flow rate is equivalent to the flow rate specified by the analytical protocol. Measure the eluent
flow rate after the column using a stopwatch and graduated cylinder.
6.5
Spurious Peaks
A. If the samples contain an appreciable level of polyvalent ions and the column is used with a weak eluent system,
polyvalent anions may contaminate the analytical column. The retention times for the analytes will then decrease and
spurious, inefficient (broad) peaks can show up at unexpected times. Clean the column as indicated in “Column Care.”
B. If you need assistance in determining the best way to clean strongly retained solutes in your specific sample matrix
from the IonPac AS9-SC columns, contact the nearest DIONEX Worldwide Office (see, DIONEX Worldwide
Offices).
C. When an injection valve is actuated, the possibility of creating a baseline disturbance exists. This baseline upset can
show up as a peak of varying size and shape. This will occur when the injection valve needs to be cleaned or retorqued
(see valve manual). Check to see that there are no restrictions in the tubing connected to the valve. Also check the valve
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