A derivatization method is applied to chemically modify the glucose molecules. Then the derivatized C1 and C2 labeled glucose can be differentiated by tandem mass spectrometry. A multiple reaction monitoring method is developed to quantify the C1- and C2-13C labeled glucose, with deuterated glucose as the internal standard.Based on the fragmentation of cross-linked amino acids (pyridinoline (PYD) and deoxypyridinoline (DPD)), a precursor ion scan method is developed to detect DPD and PYD from a complex matrix. DPD is detected in a hydrolyzed mouse ventricle collagen sample by this method.A series of peptides and proteins are successfully ionized by a home made DESI source. The investigation of the sample surface effect shows that self assembled monolayer surfaces produce better signal than bare gold surfaces, implying that this is due to the lower electron transfer on SAM film which allows more ions to survive.