Solvents for LCMS experiments must be compatible with the mass spectrometer. (This is also true for any mobile phase modifier you might wish to use.) Solvents for LCMS should also be compatible with the ionization method to be used.

Safe solvents include water, acetonitrile, methanol. Other solvents must be approved by the MS facility manager prior to use.

Safe mobile phase modifiers:

• volatile organic acids and/or bases (e.g., acetic acid, formic acid, ammonium acetate)
• alkyl ammonium salts of volatile organic acids may be used, but the alkylammonium cation will often dominate the positive ion spectrum
• trifluoroacetic acid and heptafluorobutyric acid are permissible but should only be used with caution and only when necessary as they can cause ion supression and intense chemical background noise

Forbidden mobile phase components:

• mineral acids and salts thereof (including inorganic phosphates)
• inorganic bases (e.g., NaOH) and salts thereof
• other inorganic salts
• chlorinated solvents
• involatile organics
• buffers composed of materials not described in the "Safe Mobile Phase Modifiers" section
• anything yielding an extreme pH (i.e., less than 2 or greater than 10)
• particulate matter, a.k.a. "floaties"
• anything else which may harm the instrumentation