We report a method of small molecule analysis using a converted graphene-like monolayer (CGM) plate and laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) without organic matrices. The CGM plate was prepared from self-assembled monolayers of biphenyl-4-thiol on gold using electron beam irradiation followed by an annealing step. The above plate was utilized for the LDI-TOF MS analyses of various small molecules and their mixtures, e.g., amino acids, sugars, fatty acids, oligoethylene glycols, and flavonoids. The CGM plate afforded high signal-to-noise ratios, good limits of detection (1 pmol to 10 fmol), and reusability for up to 30 cycles. As a practical application, the enzymatic activity of the cytochrome P450 2A6 (CYP2A6) enzyme in human liver microsomes was assessed in the 7-hydroxylation of coumarin using the CGM plate without other purification steps. We believe that the prepared CGM plate can be practically used with the advantages of simplicity, sensitivity, and reusability for the matrix-free analysis of small biomolecules.
Bibliographical noteFunding Information:
This research was supported by the Priority Research Centers Program (2009-0093824) through the National Research Foundation (NRF) of Korea (NRF-2016R1D1A1A09918111 and NRF-2015R1A2A2A05050829) funded by the Ministry of Education and by the Agri-Bio Industry Technology Development Program (316028-3, Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (IPET)).
© 2017 Elsevier B.V.
- Converted graphene-like monolayer
- Laser desorption/ionization time-of-flight mass spectrometry
- Self-assembled monolayers
- Small biomolecules