Chromatography Forum

Recently I am having problems of electrodes. The signal from new electrodes keeps lowering when running samples and goes away in less than one day. The electrodes are brand new, and I have tried 4 of them. So gotta be some where else in the system goes wrong. Anyone in this forum could figure out the problem? Thank you.

A few questions to help troubleshoot:

• When was your reference electrode last replaced? They should be replaced every ~6 months on the ICS3000.
• What is your total signal?
• Is the mode set correctly (IntAmp vs. DCAmp)?
• Is the reference electrode set correctly (AgCl vs. pH)?
• Which waveform are you using?
• What is the physical condition of the disposable electrodes when you remove them (i.e., is the gold plating worn away?)

There is some blurb in the article below on the eating of gold electrodes and the bod recommends a quadruple wave function etc for PAD. Page 483


http://quimica.udea.edu.co/~carlopez/cr ... hap_07.pdf



But is all voodoo black magic to me and I reckon they make all the theory up.

I have never used disposable gold electrodes and still have the same ones from 20 years ago I have no idea how people trash them so easily.

I tend to stick to lowest possible sample size and never polish them and just use a pencil rubber to clean them.

There are two possible causes for the problem you describe:

1). You are using the old triple pulse waveform. This waveform is not compatible disposable electrodes. You should be using the quadruple pulse waveform which was optimized for disposable electrodes.
2). Your reference electrode is defective. To obtain acceptable life with disposable electrodes it is important that the potentials of the waveform be at the correct values. With an older reference electrode the apply potentials can be significantly different from the expected values. When was the last time you change your reference electrode? If the reference electrode is discolored or opaque it should be replaced.

Hi Wangy,

Further to Chris' response can you also provide us with you eluant conditions the gradient profile, whether this is run with reagent free KOH or a manually prepared eluant KOH/NaOH with Sodium Acetate as the pusher salt.


Mark Albertson
Thermo Fisher Scientific
Sales Mgr ANZ.
HPLC, IC, Sample Prep