I am immunoprecipitating a protein for analysis by mass spect and I was told to minimize tris and also PEG for a clear analysis by mass spectrometry. I lysed in RIPA buffer with 50 mM tris and 1% Np40 (containing PEG) and so I would like to wash this away in my IP and ship the final bead-antibody-protein complex in buffer without detergent and with low tris. I was considering going down to 25 mM tris, or simply replacing my formula with another buffer with a similiar pH, such as HEPES.

What are your thoughts on RIPA buffer for mass spect analysis. What are the best recipes to minimize background and still keep the protein in tact?

Full current formula: 50 mM Tris base, 1% NP-40, 0.1% SDS, 0.5% DOC, 150 mM NaCl, qH2O, Anti-proteases & Anti-phosphatases: NaF, Active Na Orthovanidate, and PICIII