Background Ions
Posted: Thu May 17, 2018 12:13 pm
I am getting background ions of 110.1, 154.9, and 436.3 throughout each sample acquisition, but I am mainly concerned with m/z 436.3. The mobile phases I use are 0.1% formic acid in H2O and 100% ACN. I thought the contamination was inside the mass spec because whatever I infused would give me m/z 436.3 so I cleaned the Ion Transfer tube, changed needle insert and also cleaned the skimmer cone in case any build-up was present. Afterwards, I infused my mobile phases starting with ACN and it came back clean with minimal background ions. I infused the 0.1% formic acid in H2O mobile phase and it showed m/z 436.3 like before. Then I infused straight H2O (Millipore reagent water) and it was still there so I moved to deionized water and had no luck. I even saw trace amounts of it when I infused MeOH.
Is it possible that BOTH water sources are contaminated and what exactly is m/z 436.3? I can't find it anywhere online. Is there anything else I should try or has anyone else had this kind of problem before? Also, any ideas about the other two ions present in my spectrum?
Is it possible that BOTH water sources are contaminated and what exactly is m/z 436.3? I can't find it anywhere online. Is there anything else I should try or has anyone else had this kind of problem before? Also, any ideas about the other two ions present in my spectrum?