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IonPac AS3, AS4, AS5, CS2
5.2.5 A Contaminated Self-Regenerating Suppressor (SRS
If the above items have been checked and the problem persists, the SRS or the MMS is probably causing the problem.
A. Check the regenerant flow rate at the REGEN OUT port of the SRS or the MMS. For the example isocratic applications,
this flow rate should be 3 - 5 mL/min in the Chemical Suppression Mode of operation.
B. Check the eluent flow rate. The eluent flow rate for most 4-mm applications should be 2.0 mL/min. Refer to the Anion
Self-Regenerating Suppressor Product Manual (Document No. 031367), the Cation Self-Regenerating Suppressor
Product Manual (Document No. 031370), the Anion MicroMembrane Suppressor Product Manual (Document No.
031728) or the Cation MicroMembrane Suppressor Product Manual (Document No. 031728) to ensure that the eluent
is within suppressible limits.
C. If you are using an AutoRegen
fresh regenerant solution. Test both the suppressor and the AutoRegen Regenerant Cartridge for contamination.
1. If the background conductivity is high after preparing fresh regenerant and bypassing the AutoRegen Regenerant
Cartridge, you probably need to clean or replace your SRS or MMS.
2. If the background conductivity is low when freshly prepared regenerant is run through the SRS or MMS without
an AutoRegen Accessory in-line, test the AutoRegen Regenerant Cartridge to see if it is expended. Connect the
freshly prepared regenerant to the AutoRegen Regenerant Cartridge. Pump approximately 200 mL of regenerant
through the AutoRegen Regenerant Cartridge to waste before recycling the regenerant back to the regenerant
reservoir. If the background conductivity is high after placing the AutoRegen Accessory in-line, you probably need
to replace the AutoRegen Regenerant Cartridge. Refer to the "AutoRegen Regenerant Cartridge Refill Product
Manual" (Document No. 032852) for assistance.
5.3
Poor Peak Resolution
Poor peak resolution can be due any or all of the following factors.
5.3.1 Loss of Column Efficiency
A. Check to see if headspace has developed in the guard or analytical column. This may be due to the 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, the resin bed has
collapsed, creating a headspace. The column must be replaced.
B. Extra-column effects can result in sample band dispersion, making the peaks' elution less efficient. Make sure you
are using tubing with an ID of no greater than 0.012" 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.
5.3.2 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. Check the flow rate. See if the eluent flow rate is faster than the flow rate specified by the analytical protocol. Measure
the eluent flow rate after the column using a stopwatch and graduated cylinder.
B. Check to see if the eluent compositions and concentrations are correct. An eluent that is too strong will cause the peaks
to elute faster. Prepare fresh eluent. If you are using a gradient pump to proportion the eluent, components from two
or three different eluent reservoirs, the resulting eluent composition may not be accurate enough for the application.
Use one reservoir containing the correct eluent composition to see if this is the problem. This may be a problem when
Document No. 032226-14
®
Accessory with the SRS (in the Chemical Suppression Mode) or the MMS, prepare
) or the MicroMembrane
™
Page 13 of 14
Suppressor (MMS)
™
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