The Structural Influence of Graphene Oxide on Its Fragmentation during Laser Desorption/Ionization Mass Spectrometry for Efficient Small-Molecule Analysis.

The structural influence of graphene oxide (GO) on laser desorption/ionization mass spectrometry (LDI-MS) analysis of small molecules was systematically investigated by using size-fractionated GO. For fractionation of GO, pH-assisted centrifugation, sequential vacuum filtration, and sonochemical cutting processes were employed and the size-fractionated GO was thoroughly characterized to understand their size-dependent optochemical properties. Then, the fractionated GO was applied to the analysis of various small molecules by LDI-MS to investigate the relationship between their optochemical properties and LDI-MS performance. We found that large GO sheets (>0.5 μm) were more prone to fragmentation under laser irradiation during LDI-MS analysis than small GO sheets (<0.5 μm). In this regard, the LDI-MS analysis efficiency of various small molecules was significantly improved by using nanosized GO (NGO) as a matrix without background interference. In particular, NGO was successfully applied to the sensitive detection of hydrophobic pollutant molecules without requiring any surface-functionalization, enrichment, and separation process. Therefore, the present study could provide important basic information and be a practical tool for the development of simple and efficient LDI-MS platforms by using GO derivatives.