Ion desorption efficiency and internal energy transfer in polymeric electrospun nanofiber-based surface-assisted laser desorption/ionization mass spectrometry

The understanding of the desorption mechanism in surface-assisted laser desorption/ionization (SALDI) remains incomplete because there are numerous types of SALDI materials with a broad range of physical and chemical properties, many of which impact the ultimate analytical performance in terms of signal generation. In this study, the chemical thermometer molecule, benzylpyridinium chloride, is applied to investigate the desorption process of SALDI using electrospun nanofibrous polymer and polymer composite substrates. The ion desorption efficiency was inversely related to the ion internal energy, which could not be fully explained by a thermal desorption mechanism. A competing non-thermal desorption (i.e., phase transition/explosion) was proposed to be involved in this SALDI process. The influence of the orientation and dimension of the nanofiber structure revealed that a cross-linked nanofiber network with a small diameter favored the nanofiber-assisted LDI to provide efficient ion desorption.