Reduced Sampling Size with Nanopipette for Tapping-Mode Scanning Probe Electrospray Ionization Mass Spectrometry Imaging

Abstract

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.

Direct Liquid Extraction and Ionization Techniques for Understanding Multimolecular Environments in Biological Systems (Secondary Publication)

“…Thus, higher ionization efficiency can be expected due to the solvent volume effect in ESI described below. Using a probe with a fine tip shape provides extraction areas of 5-6 µm 140) . MSI by t-SPESI has been applied to mouse brain 138) and mouse pancreatic cancer samples 141) .…”

Visualization of Sampling and Ionization Processes in Scanning Probe Electrospray Ionization Mass Spectrometry

“…In addition, the use of a nanopipette simultaneously permitted a reduction in the sampling area and increased the ionization efficiency. 13)…”

Towards Practical Endoscopic Mass Spectrometry

“…By using a suitable solvent, the compound on the surface dissolves into the solvent formed in the liquid junction interface, or liquid bridge, and is transported to the ion source such as ESI. is method has been used in "liquid sampling probe ESI" by Van Berkel et al, 22) nano desorption electrospray ionization ("nano-DESI") by Julia Laskin et al, 23) scanning probe ESI by Arakawa, 24,25) and "theta" capillary ESI probe (a double-barrel capillary that resembles the Greek letter θ "theta" when turned on end). 26) ii) Gas phase/aerosols sampling e sample is vaporized using heater or laser and the thermally desorbed sample vapor or the ablated aerosols, or both, are carried by compressed air ow or suction to the suitable ion source.…”