Mass spectrometry imaging (MSI) with ambient sampling and ionization can rapidly and easily capture the distribution of chemical components in a solid sample. Because the spatial resolution of MSI is limited by the size of the sampling area, reducing sampling size is an important goal for high resolution MSI. Here, we report the rst use of a nanopipette for sampling and ionization by tapping-mode scanning probe electrospray ionization (t-SPESI). e spot size of the sampling area of a dye molecular lm on a glass substrate was decreased to 6 µm on average by using a nanopipette. On the other hand, ionization e ciency increased with decreasing solvent ow rate. Our results indicate the compatibility between a reduced sampling area and the ionization e ciency using a nanopipette. MSI of micropatterns of ink on a glass and a polymer substrate were also demonstrated.
We report the application of tapping-mode scanning probe electrospray ionization (t-SPESI) to mass spectrometry imaging of industrial materials. The t-SPESI parameters including tapping solvent composition, solvent flow rate, number of tapping at each spot, and step-size were optimized using a quadrupole mass spectrometer to improve mass spectrometry (MS) imaging of thin-layer chromatography (TLC) and additives in polymer films. Spatial resolution of approximately 100 μm was achieved by t-SPESI imaging mass spectrometry using a fused-silica capillary (50 μm i.d., 150 μm o.d.) with the flow rate set at 0.2 μL/min. This allowed us to obtain discriminable MS imaging profiles of three dyes separated by TLC and the additive stripe pattern of a PMMA model film depleted by UV irradiation.
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