On-tissue chemical derivatization of volatile metabolites for matrix-assisted laser desorption/ionization mass spectrometry imaging

Mass spectrometry imaging (MSI) of volatile metabolites is challenging, especially in matrix-assisted laser desorption/ionization (MALDI). Most MALDI ion sources operate in vacuum, which leads to the vaporization of volatile metabolites during analysis. In addition, tissue samples are often dried during sample preparation, leading to the loss of volatile metabolites even for other MSI techniques. On-tissue chemical derivatization can dramatically reduce the volatility of analytes. Herein, a derivatization method is proposed utilizing N,N,N-trimethyl-2-(piperazin-1-yl)ethan-1-aminium iodide to chemically modify short-chain fatty acids in chicken cecum, ileum, and jejunum tissue sections before sample preparation for MSI visualization.