Synthesis of magnetic microspheres with immobilized metal ions for enrichment and direct determination of phosphopeptides by matrix-assisted laser desorption ionization mass spectrometry

Core/shell structured magnetic silica microspheres with immobilized Fe3+ (see image) are prepared with a simple method. Using a magnetic field, the microspheres are quickly, efficiently, and specifically enriched. Phosphopeptide identification can then be achieved through mass spectroscopy. This is a new method for the enrichment of phosphopeptides and opens up the possibility of other new applications using the microspheres.