Polyacrylonitrile-based carbon nanofibers as a matrix for laser desorption/ionization time-of-flight mass spectrometric analysis of small molecules under both positive and negative ionization modes.

Carbon fiber (CNF), prepared by carbonization of electrospun polyacrylonitrile (PAN) fibers, is systematically investigated as a mediator to replace conventional organic matrices for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS). CNF exhibits a high salt tolerance, sensitivity, and resolution for organic matrix-free laser desorption/ionization time-of-flight mass spectrometry (LDI-MS) analysis of various analytes under both positive and negative ionization modes. Especially, saccharides, a neutral molecule having low negative ionization efficiency, are successfully detected with CNF. Taken together, this study clearly demonstrates CNF is a promising material to develop an efficient and universal platform for LDI-MS analysis regardless of preferential ionization modes of analytes. Graphical abstract.