Nano-flow ionization is a soft ionization technique that is particularly useful for analyzing biological samples such
as proteins and peptides. It uses very small volumes of sample and takes full advantage of the benefits of capillary
chromatography. It also preserves the sample integrity and reduces fragmentation.
The Curtain Gas
TM
flow improves the laminar flow of ions toward the orifice plate aperture, creating smaller droplets
that ionize more efficiently and produce a higher yield of useful ions. The interface removes larger particles from
the ion current before they enter the aperture.
Figure A-1 Ion Evaporation
Description
Item
Droplet contains ions of both polarities with one polarity being predominant.
1
As the solvent evaporates, the electrical field increases and the ions move to the surface.
2
At some critical field value, ions are emitted from the droplets.
3
Nonvolatile residue remains as a dry particle.
4
Each charged droplet contains solvent, positive ions, and negative ions, but with one polarity predominant. The
surface of each droplet contains an excess of charges. As the droplets evaporate, the radius of the droplet shrinks,
and the electrical field at the surface increases.
If the droplet contains excess ions, and enough solvent evaporates from its surface, a critical point is reached at
which ions are ejected into the gas phase by a very low energy process that does not induce fragmentation. After
the solvent evaporates, it leaves a dry particle consisting of the non-volatile components from the sample.
Operator Guide
NanoSpray
®
Ion Source
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A
Principles of Operation
