Hi, I'm Using Ion Chromatography.

I have used suppressed analysis in cation channel.
But I had to check the direct conductivity detection analysis in cation channel, So I tried it.

But There are serious wavy and fluctuation in baseline.
If I use the channel with cation suppressor, There is no problem.
The noise is very low.
But If I use direct conudctivity detection, there is too high noise regardless of column.
I tried Shodex YS-50, Sykam C07 which are possible to be used in suppressed and direct conductivity detection.

Regardless of the type of eluent, such as 5mM MSA, 3mM MSA, 2mM oxalates, 3mM DPA there is same symptom.

I tried followings:

1. change and check pump head

2. Change Chemicals to new one

3. get rid of air bubble in conductivity cell

The water conductivity was 0.055 uS/cm (18.2 mOhm) when I get it from water purification machine.

I checked the chromatograms acquired in April, there was no such a high noise.

Does anyone have any idea?