Peak phosphate getting small and broad (ICS-5000)

[Ash Burnt]

Hello,

What to do when phosphate peak getting broad and small?
We used around 0.1-0.4ppm as standard 1,2 and 3 respectively.
The recovery for std 1 and 2 are not good. Thus affect the Coeff. Of determination of phosphate.
But there is no problem with micropipette.
We control our Coeff. Of Det. 99.5% above.
We also control the slope and fixed the offset to zero.
From our observation the Coeff.Det. and slope getting decreases and the peak look broad and small (standard 2 & 3). We want high and sharp peak.
We already used new suppressor.
But after use it for 3 weeks, the problem occurs for phosphate only.
Other ions are within control except phosphate.
What should we do?

Thanks.

[Markus Laeubli, Metrohm]

When phosphate is getting too small usually a contamination of the IC with iron is the reason.

[Ash Burnt]

Thank you.
But how to solve this matter?
We already clean the suppressor with IPA, 0.5N H2S04 and purified water.
But the peak still broad and small.
Then we change the concentration of eluent generator.
The peak became sharp but relative area and height of the peak is lower than usual
caused the slope of phosphate is still in lower site of our control limit.
Anyone have any suggestion?

Thanks.

[Markus Laeubli, Metrohm]

On Metrohm IC systems we use sulfuric acid/oxalic acid/ acetone regeneration of the Metrohm Suppressor Module. Check with your service rep about possibilities.

[Ash Burnt]

Thanks for sharing.
Actually our IC system is still ok because we still can get Coeff. Of Det. 99.5% above and ICV recovery within 80-120% but we have to control the offset and slope. When the offset or slope of any element is out of control limit, we have to take action in order to get all within control limit. Right now, we always having slope issue. We have to think the solution by our self and ask anyone instead of calling service engineer or buying spare part in order to reduce our budget.
Did anyone struggle like us?
How to control slope?
It is really difficult to control all things.