Nanospray desorption electrospray ionization

Nanospray desorption electrospray ionization (nano-DESI) is an ambient pressure ionization technique used in mass spectrometry (MS) for chemical analysis of organic molecules.[1] In this technique, analytes are desorbed into a liquid bridge formed between two capillaries and the sampling surface.[2] Unlike desorption electrospray ionization (DESI), from which nano-DESI is derived, nano-DESI makes use of a secondary capillary, which improves the sampling efficiency.[1]

Typical setup of a nanospray desorption electrospray ionization probe.

Principle of operation

The typical nano-DESI probe setup consists of two fused silica capillaries - primary capillary which supplies solvent and maintains a liquid bridge, and secondary capillary which transports the dissolved analyte to the mass spectrometer.[1] High voltage (several kV) is applied between the inlet of the mass spectrometer and the primary capillary, creating a self-aspirating nanospray. The liquid bridge is maintained by continuous flow of the solvent and the contact area between the solvent bridge and sample surface can be controlled by changing the solvent flow rate, varying the diameter of the utilized capillaries and regulating the distance between the sample and the nano-DESI probe.[3] In this way, the spatial resolution in mass spectrometry imaging applications can be improved, with typical resolution ranging between 100 - 150 μm.[4]

Applications

Nano-DESI has been applied for localized analysis of complex molecules and imaging of tissue sections, microbial communities and environmental samples.[5]

References
  1. Roach PJ, Laskin J, Laskin A (September 2010). "Nanospray desorption electrospray ionization: an ambient method for liquid-extraction surface sampling in mass spectrometry". The Analyst. 135 (9): 2233–2236. Bibcode:2010Ana...135.2233R. doi:10.1039/C0AN00312C. PMID 20593081.
  2. Hotta K, Takeda K, Iinoya K (1974-10-01). "The capillary binding force of a liquid bridge". Powder Technology. 10 (4): 231–242. doi:10.1016/0032-5910(74)85047-3. ISSN 0032-5910.
  3. Laskin J, Lanekoff I (January 2016). "Ambient Mass Spectrometry Imaging Using Direct Liquid Extraction Techniques". Analytical Chemistry. 88 (1): 52–73. doi:10.1021/acs.analchem.5b04188. PMC 5767520. PMID 26566087.
  4. Lanekoff I, Laskin J (2015). "Imaging of lipids and metabolites using nanospray desorption electrospray ionization mass spectrometry". In He L (ed.). Mass Spectrometry Imaging of Small Molecules. Methods in Molecular Biology. Vol. 1203. New York, NY: Springer New York. pp. 99–106. doi:10.1007/978-1-4939-1357-2_10. ISBN 978-1-4939-1356-5. PMID 25361670.
  5. Lanekoff I, Heath BS, Liyu A, Thomas M, Carson JP, Laskin J (October 2012). "Automated platform for high-resolution tissue imaging using nanospray desorption electrospray ionization mass spectrometry". Analytical Chemistry. 84 (19): 8351–8356. doi:10.1021/ac301909a. PMID 22954319.
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