Chromatography Forum

Hello

I've ten years experience in IC included my degree on validation of IC methods.
I've experienced a crytical problem with my new ICS1100 running with AS9HC & carbonate 9mM eluent.
i try to describe the situation.
the system is new, it worked fine for a few months but now i experienced a drammatic decrease in retention times of all anion peaks.
It starts with change in resolution of sulphate/Posphate... continues with sovrapposition of Nitrate with sulphate+posphate & ends with death of column.
I use the same eluent & water since 10 years.
Water is bi-distilled & filtered with conductivity usually < 1uScm-1.
Carbonate is (i wish) as pure as possible.
Contaminants that kills colums that i know are:

-CrVI (it's absent i've controlled it AA it's >LOD in flame i can control in A.A./E.T.A. but i want to exclude ppB levels i don't believe it's present

- grease (the system is completly new ics 1100 it mustn't have problems with grease i wish

- all the lines for eluents are inert

- i've checked eluent for presence of fe3+ but it's < LOD in flame

- i've thinked about free Cl2 in water but it's bidistilled water...
& i don't know what's the effect of cl2 on PSDVB polymers

i don't know what to look for.

It kills AS9-HC & i've fear that it contaminate the system!!!!!
What should it be?

I'm desperate i'll request a dionex visit but i don't know what's the problem.

The eluent is prepared with the same procedure (column data sheet) since ten years: mother solution .... diluition to 9mM carbonate.... etc....

HELP ME.

Treat yourself to a bottle of HPLC-grade water, or at the very least, a milli Q apparatus.

I would pump 40 mM Na2EDTA through your system (and column, but not detector) o/n at a low flow rate. Follow this with water, then several column volumes 0.5 M NaClO4 20 % MeCN, followed by water, then re-equilibrate with your mobile phase.

Consider using a cation exchange guard, or, better yet, a WCX-SAX mixed-bed guard. Exogenous Fe+++ is known to bind strongly to SAX columns, deteriorating performance. The WCX guard will mop up Fe+++ in the mobile phase, preventing it from fouling the analytical column.