Ion exclusion column problem

[joelyue]

Hi,

i have a Dionex AS6 ICE column in which my eluent is UPW and the samples i inject are 25% HF.

The problem is that the column loses its efficiency within 3 months and i have no idea why.

When the column is new, my sample is totally eluted from the column within 45mins. However 3 month down the road, with no prior warning signs at all, it now take 90mins to totally elute the injected sample.

As it now takes twice the time per sample, i would like to understand why before i purchase a new column bcos i dont want the same happening to the new column too.

Has anyone faced the same problem as mine? Please share.

[joelyue]

Anyone out there uses the same IC column as mine?

[Mark Tracy]

I asked one of our specialists about your question, and he wanted more info. Are you analyzing for fluoride or something else? Can you post example chromatograms?

[joelyue]

I am actually analyzing chloride in hydroflouric acid using the setup as mentioned in Dionex Technical Note 45.
Will post a chromatogram once i get hold of it.

[mdfenko]

the elution time just doubled overnight?

have you checked your pump?

[Chris Pohl]

joelyue,

Unfortunately, the application you are using is pretty demanding with regard to column lifetime. Depending upon your injection volume, the column life you are reporting seems fairly normal. In general, you will get better column life for this application using the IonPac ICE AS1 column but even in this case the column life will not be more than double what you're experiencing. The problem is that the gel-based materials used to make ion exclusion columns shrink when exposed to a high ionic strength and repeated injections of concentrated samples will generally cause compaction of the column bed. The best way to prolong column life is to minimize your injection volume or your sample concentration but I know in this case that this is generally not an option since the sensitivity requirements for the application are fairly demanding.

Chris