RP-LC/MS Standard

[Johte]

Hello all,

I'm running Ammonium acetate/Acetonitrile gradients on 75 um C18 columns that I pack. I spray specifically in negative mode for nucleic acids so I'd like to have something larger in the mix.

I was hoping someone had some suggestions of what compounds I could use as the typical RP standards are not ideal for negative mode. ( Uracil, caffeine, etc)

Much obliged!

[kmchale]

Johte,

I regularly use the antibiotic Chloramphenicol to evaluate LC/MS systems in negative ESI mode.