Techniques Used By Analytical Chemist For The Creation Of Ions From A Sample

1454 WordsOct 15, 20146 Pages
Electrospray is the technique that is used by analytical chemist for the creation of ions from a sample. The technique uses electricity to form an exceptionally fine liquid aerosol. Other techniques that were used before electrospray used gas to form these aerosols for analyses. Electrospray is particularly useful over using gas because it is a soft ionization technique. Soft ionization techniques ionize the sample with minor fragmentation of the molecule, giving an observable molecular ion for the mass spectrometer to measure. This is an advantage in macromolecules because old techniques use to fragment the larger molecule. Going from solution to ions using electrospray is an interesting process. The analyte or sample that is being…show more content…
These droplets are around 10 micrometers in size depending on the analyte. The droplets contain a mixture of the solvent it was dissolved in and the analyte. Once the cloud of tiny droplets, the aerosol, is created and expelled from the nozzle the solvent present in the droplet starts to evaporate from the surface of the highly charged small droplet. The electrospray instrument can be heated to aid in the evaporation of said solvent creating a highly charged droplet that is reaching its Rayleigh limit, the surface tension on the droplet cannot maintain the charge. However, as the solvent evaporates the distance between the charged droplets are decreasing as a function of solvent present. As the droplets are subjected to a higher force of electrostatic repulsion they become more and more unstable as a droplet. Once the electrostatic repulsion becomes higher than that of the surface tension of the droplet it will undergo Coulomb fission. The basic idea here is that the original highly charged droplet will become smaller as the solvent evaporates off until it becomes so small that it cannot handle the charge present and the droplet will burst. The droplet will burst because it will need to dissipate the charge present. The original droplet will burst into smaller droplets that are less charged and more stable than the original droplet. This keeps happening to all of the
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