Ambient in situ analysis and imaging of both hydrophilic and hydrophobic thin layer chromatography plates by electrostatic spray ionization mass spectrometry

Electrostatic spray ionization (ESTASI) mass spectrometry imaging (MSI), recently developed to profile spatial distribution of chemical and biochemical molecules on an insulating surface under ambient conditions, has been applied to identify and quantify chemicals from silica gel surfaces. Both hydrophilic or hydrophobic silica plates have been imaged with good resolution providing a direct identification of the samples. For the hydrophilic silica gel substrate, silanization of the plate before ESTASI-MS analysis was used to render the surface hydrophobic. ESTASI-MSI is shown to be a sensitive technique for the identification of a wide range of molecules of different polarities and chemical structures with minimal sample consumption in the femtomole range.