Poor Resolution/Early Elution on New Column

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2 posts Page 1 of 1
Hi all,

I am new to Ion Chromatography and need some troubleshooting advice as to why I'm seeing poor resolution on my column for a couple of early eluting anions upon installation of a brand new column.
I operate a Dionex ICS-5000 with an IonPac AS5A-5u Analytical Column; two anions we analyze in our samples are acetate and glycolate, which start to co-elute more and more as the column ages.

1) I just installed new guard and analytical columns on both sides of the instrument and ran calibration standards ranging from 1-100 ppm and get perfect resolution of these compounds on one column but zero resolution on the other side starting at the 25 ppm concentration.
2) The retention time for these two compounds on the good column is 5.2 min for acetate and 5.8 min for glycolate but I see much earlier elution around 2.5-2.8 min on the other column.
3) I conditioned the guard and analytical columns the same way for both, running eluent through the guard and column individually for 30 min at operating flow rate before connecting to the rest of the system.

The method parameters are the same on both sides:
Flow rate: 1.00 mL/min
Eluent 1: 0.50 mM KOH for 12 min
Eluent 2: 100 mM KOH at min 30
Generated using a Dionex Eluent Generator Cartridge. The EGC for the good side was replaced at the same time as the column whereas the EGC on the bad side has been running for awhile and is at 30% remaining.
Column Temp: 30 Celsius
Injection volume:100 uL

According to the column manual there are a few potential reasons for loss of front end resolution due to shortened retention times such as checking the flow rate, if the eluent compositions and concentrations are correct and for column contamination. I am pretty confident none of these are the reason I'm seeing such a difference between the two sides, and I'm thinking I just have a defective column (the lot numbers are different for the columns and the columns running previously on both sides are the same number as this defective column and they deteriorated much quicker than normal.)
Hi jmurray2,

I manage these columns and would like to help with your issue. Please contact me directly via email (john.guajardo@thermofisher.com) and, if possible, send Chromeleon cmb(x) files showing a few injections when everything was fine with your system vs. now with the resolution issues. Also, please include the serial numbers of the columns you recently installed.
Best regards,

John Guajardo
Product Manager, IC Columns
Thermo Fisher Scientific
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