Covalent organic framework as efficient desorption/ionization matrix for direct detection of small molecules by laser desorption/ionization mass spectrometry.

Covalent organic framework (COF) was explored as a novel matrix with a high desorption/ionization efficiency for direct detection of small molecules by laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS). By using COF as an LDI MS matrix, we could detect not only biological micro molecules such as amino acids and fatty acids, but also emerging environmental pollutants like bisphenol S (BPS) and pyrene. With COF as the matrix, higher desorption/ionization efficiency, and less background interference were achieved than the conventional organic matrices. Good salt tolerance (as high as 500 mM NaCl) and repeatability allowed the detection limit of amino acids was 90 fmol. In addition, COF matrix performed well for amino acids analysis in the honey sample. The ionization mechanism was also discussed. These results demonstrate that COF is a powerful matrix for small molecules analysis in real samples by MS.