Hi,
so far I have only worked with proteins and peptides but now a colleague of mine wants me to analyze some nucleotides (cytidines) on our ltq orbitrap xl. I have purchased the pierce negative ion calibration juice and just tuned the instrument on the sds peak. I'm planning to use a short C18 column for some separation.
The question that i have now is:
I'm using 0.1% TFA and 0.05% Formic Acid in my solvents (A = water and B = 80 % ACN). Those are leftovers from my last protein/peptide experiment (in positive polarity mode). Do I need to change the ion pairing additives in the solvents?

What about the calibration of the instrument? First positive ion juice (MRFA, Caffeine, Ultramark etc) and then for the negative part the negative ion solution?

So many stupid questions - I apologize. But this is something new to me.
Looking forward to your help & advice.
Thanks a bunch