Ion Chromatography

Hi guys. First time posting on Reddit!

I am having issues running the IC at the company I work for. I am the only chemist/R&D out of 400 people and have no one to turn to. I am analyzing nitrates and nitrites in powdered milk samples, but have been having trouble correctly determining known concentrations in these samples. I have completed a standard curve of both analytes with an R^2 of .998. With that being said, every time I run a milk powder of known concentration, I am not receiving any peaks(minimal at best) for the substances in question.

I am hesitant to change the mobile phase concentration (KOH) and suppressor settings, because these analytes are detected using the same protocol as the standards. My guess would be that there is something wrong with my method of processing the sample?

I am currently adding .5ml 3% acetic acid solution (separate fat and protein) to .5g sample in 24ml water. The pH value is around 5.30.

I’ve made “spiked” samples of dry milk powder and have run them with success, but am unable to quantify the analytes in samples I’ve received as proficiencies.

I’ve had no training in my position and have started from the absolute bottom with this machine. The previous chemist before me failed his proficiencies and bailed soon after.

The purpose of this post is to hopefully come across another nerd that likes peaks and has an answer.