# Chemical Sciences: A Manual for CSIR-UGC National Eligibility Test for Lectureship and JRF/Ambient ionization

Ambient ionization is a form of ionization in which ions are formed outside the mass spectrometer without sample preparation or separation.

## Direct analysis in real time

Direct analysis in real time (DART) is an atmospheric pressure ion source that operates by exposing the sample to a gas stream (typically helium or nitrogen) that contains long-lived electronically or excited neutral atoms, vibronically excited molecules (or "metastables"). Excited states are formed in a glow discharge in a chamber through which the gas flows..

## Desorption electrospray ionization

Desorption electrospray ionization (DESI) uses an electrospray source to create charged droplets that are directed at a solid sample. The charged droplets pick up the sample through interaction with the surface and then form highly charged ions that can be sampled into a mass spectrometer.

## Desorption atmospheric pressure photoionization

Desorption atmospheric pressure photoionization (DAPPI) enables direct analysis of samples deposited on surfaces by means of a jet of hot solvent vapour and ultraviolet light. The hot jet thermally desorbs the sample from a surface and the vaporized sample is ionized by a vacuum ultraviolet light and consequently sampled into a mass spectrometer.

## Laser assisted

Electrospray-assisted laser desorption/ionization (ELDI) relies on a laser to the desorption of material into the electrospray plume. With matrix-assisted laser desorption electrospray ionization (MALDESI), a nitrogen laser is used to desorb material into the electrospray. MALDESI has been used with MALDI matrix materials. Laser ablation electrospray ionization (LAESI) uses an infrared laser for ablation of the sample material. The term laser spray ionization has been used to describe transmission mode laser ablation coupled with electrospray ionization.

## References

* ↑ Cooks, R. Graham; Ouyang, Zheng; Takats, Zoltan; Wiseman, Justin M. (2006). "Ambient Mass Spectrometry". Science. 311 (5767): 1566. doi:10.1126/science.1119426. PMID 16543450.
* ↑ R.B. Cody, J.A. Laramée, H.D. Durst (2005). "Versatile New Ion Source for the Analysis of Materials in Open Air under Ambient Conditions". Anal. Chem. 77 (8): 2297–2302. doi:10.1021/ac050162j. PMID 15828760.{{cite journal}}: CS1 maint: multiple names: authors list (link)
* ↑ Takáts Z, Wiseman JM, Cooks RG (2005). "Ambient mass spectrometry using desorption electrospray ionization (DESI): instrumentation, mechanisms and applications in forensics, chemistry, and biology". Journal of mass spectrometry : JMS. 40 (10): 1261–75. doi:10.1002/jms.922. PMID 16237663.{{cite journal}}: CS1 maint: multiple names: authors list (link)
* ↑ Haapala M, Pól J, Saarela V, Arvola V, Kotiaho T, Ketola RA, Franssila S, Kauppila TJ, Kostiainen R (2007). "Desorption Atmospheric Pressure Photoionization". Anal. Chem. 79 (20): 7867–7872. doi:10.1021/ac071152g. PMID 17803282.{{cite journal}}: CS1 maint: multiple names: authors list (link)
* ↑ Shiea J, Huang MZ, Hsu HJ, Lee CY, Yuan CH, Beech I, Sunner J (2005). "Electrospray-assisted laser desorption/ionization mass spectrometry for direct ambient analysis of solids". Rapid Commun. Mass Spectrom. 19 (24): 3701–4. doi:10.1002/rcm.2243. PMID 16299699.{{cite journal}}: CS1 maint: multiple names: authors list (link)
* ↑ Sampson JS, Hawkridge AM, Muddiman DC (2006). "Generation and detection of multiply-charged peptides and proteins by matrix-assisted laser desorption electrospray ionization (MALDESI) Fourier transform ion cyclotron resonance mass spectrometry". J. Am. Soc. Mass Spectrom. 17 (12): 1712–6. doi:10.1016/j.jasms.2006.08.003. PMID 16952462.{{cite journal}}: CS1 maint: multiple names: authors list (link)
* ↑ Nemes P, Vertes A (2007). "Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass Spectrometry". Analytical Chemistry. 79 (21): 8098. doi:10.1021/ac071181r. PMID 17900146.
* ↑ Trimpin, S.; Inutan, E. D.; Herath, T. N.; McEwen, C. N. (2009). "Laserspray Ionization, a New Atmospheric Pressure MALDI Method for Producing Highly Charged Gas-phase Ions of Peptides and Proteins Directly from Solid Solutions". Molecular & Cellular Proteomics. 9 (2): 362. doi:10.1074/mcp.M900527-MCP200. PMC 2830846. PMID 19955086.