Porous anodic alumina membrane as a sample support for MALDI-TOF MS analysis of salt-containing proteins

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric (MALDI-TOF MS) analysis of proteins in salt-containing solution was performed for the first time using porous anodic alumina (PAA) membrane as sample support. The resulting spectral quality of proteins under standard sample preparation conditions was superior to that of normal metal sample stages. Analysis of phosphate-doped protein solutions indicated that porous anodic alumina membranes as a target yielded better results than a metallic target for salt-containing solutions. Because of the biocompatibility of the PAA, proteins can be adsorbed on the PAA and thus a washing process can be introduced to remove the salts from the PAA target before MS analysis. This desalting step significantly enhanced spectral quality, and better signal-to-noise ratios were obtained. The present technique is promising for proteomics research.