No peaks for some 1ppm anion standards on Dionex IC 5000

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Hello,
Sorry in advance if my IC vernacular is bad.

Our problem is this: our 1ppm standards for anions oxalate, formate, citrate and acetate have a tendency to show no peak if not made fresh. We are also running chloride, phosphate, sulphate and nitrate at the same time, but these standards have no issue at 1ppm. Our sister site that runs the same method does not see this problem. I thought maybe we have some cation contamination in our flasks or DI water causing some anion to precip out but not others.

Thoughts or ideas?

Thank you in advance!
Hi Mice Elf
I don't think that cations causes precipitation with the organic acids at this concentration level. If you have metals (cations) in your standard you would see this precipitation on the phosphate first. I think that the main problem is the stability of you 1ppm (=1 mg/l) standards.We recommend to prepare such low concentration standards fresh from a concentrated stock solution (e.g. 1000mg/L). Always use the best quality of water (18MOhm).
Regards
Stefan Brand
Thermo Fisher Scientific
Dear Mice Elf

My old friend Stefan is right. Stability most probably is the problem. Make sure that your glass/plastic ware is not contaminated with biota.
Dr. Markus Laeubli
Manager Marketing Support IC
Metrohm AG
9101 Herisau
Switzerland
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