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Mystery peak after NO2 before Br Metrohm A Supp 5

Posted: Thu Aug 10, 2017 7:17 pm
by Mritari
I am trying to identify a peak we see occasionally during routine analysis. It elutes pretty closely but after NO2. Sometimes the system identifies it as NO2 even though I made tighter acceptance windows. I am pretty sure it is the unidentified peak in the chromatogram below: Image

Re: Mystery peak after NO2 before Br Metrohm A Supp 5

Posted: Fri Aug 11, 2017 5:05 am
by Markus Laeubli, Metrohm
Dear Mritari

This peak is the system peak (also named carbonate peak). Its size depend on the hydrogen carbonate amount in the sample (not for quantification). It is minimized by use of sequential suppresson.

Best regards
Markus