For Serum and other biological samples, we Recommend using:

Solvent A: 50% DI Water/50% Methanol (or 2-propanol) + 0.1% Formic Acid (for positive mode MS) or +10 mM ammonium acetate or formate (for negative mode MS).
Solvent B: The same as you would ordinarily use.

Cleaning Tip: Methanol or 2-Propanol (IPA) helps to clean the Column between injections, which is necessary for analysis of complex matrices such as Plasma, Serum, Urine, etc. If for any reason only DI Water (with additives) has to be used as solvent A, you can add a Washing Step in the Autosampler Sequence every 10 injections using the Methanol or 2-Propanol-containing Solvent A listed above.

Related article: General solvent conditioning for TYPE-C Silica columns