Chromatography Forum

Hi,

We have a problem with a Metrohm IC system in our lab. The anion baseline is uneven and has high background conductivity, as reflected by a big water dip at the start of each chromatogram and a system peak after NO2-. I think it was caused by the suppressor drying out as a colleague may not have sufficiently topped up the H2SO4 and water bottles at the start of a run.

I have tried regenerating the suppressor with a 100mM H2SO4, 100mM oxalic acid 5% acetone solution, stepping the rotor every 15 minutes, but this has not been successful - I'm still getting a large water dip and system peak as well as an uneven baseline.

Can anyone suggest a potential solution to the problem?

Dear glj

the problem you discribe may fit to a dried out suppressor.
Please check with your Metrohm representative for an exchange.

Best regards
Markus

How old is the suppressor? My Dionex always have noisy baselines for a week or 2 before settling down. The thermo guy told me to get it running faster run some extremely high concentrated standards.

Dear Anionman

you cannot compare Dionex and Metrohm suppressors. The latter consists of three packed-bed ion exchanger compartments. These are very stable (ten years warranty) unless they dry out.
The behaviour is different from membrane containing suppressors.

10 years is impressive. I have gotten 4 out of a Dionex at most. The last one was only 18 months old when it died. the Thermo guy told me to expect about 12 months out of one. He was really impressed that I got 4 years out of one once. How much to Metrohm suppressors cost? I can't find a price online. Dionex are $1200. My lab is pretty much locked in with the Thermo equipment. We got a new Integrion last fall.

Dear Anionman
Please ask your local Metrohm representative or directly at Metrohm UA about prices.