What are the commonly used solvents for polypeptides in LCMS or MS analysis?

The preferred solvents are deionized distilled water, chromatographic grade acetonitrile, chromatographic grade methanol, and sometimes the analytically pure DMF, analytically pure DMSO, etc. Given the use of DMSO may affect the ionization effect of some polypeptide samples during dissolution thus resulting in poor test results, DMSO is only used if other solvents do not work well in dissolution or if the polypeptide cannot be dissolved with the pH having been adjusted.