{{Short description|Formation of ions in a source outside a mass spectrometer}} thumb|upright=1.3|Diagram of ambient ionization in mass spectrometry indicating desorption/extraction (spray, heat, laser), optional post-ionization (electrospray, chemical ionization, plasma), ion formation, and entry into the vacuum of the mass spectrometer. '''Ambient ionization''' is a form of ionization in which ions are formed in an ion source outside the mass spectrometer without sample preparation or separation.<ref name="Ambient ionization book (Domin, Cody)">{{cite book|last1=Domin|first1=Marek|last2=Cody|first2=Robert|title=Ambient Ionization Mass Spectrometry|date=2014|publisher=RSC (Royal Society of Chemistry)|isbn=978-1-84973-926-9|doi=10.1039/9781782628026|url=http://www.rsc.org/shop/books/2014/9781849739269.asp}}</ref><ref name=Cooks2006>{{Cite journal | last1 = Cooks | first1 = R. Graham | last2 = Ouyang | first2 = Zheng | last3 = Takats | first3 = Zoltan | last4 = Wiseman | first4 = Justin M. | year = 2006 | title = Ambient Mass Spectrometry | journal = Science | volume = 311 | issue = 5767 | pages = 1566–70 | doi = 10.1126/science.1119426 | pmid = 16543450 | bibcode=2006Sci...311.1566C| s2cid = 22007354 }}</ref><ref name="MongeHarris2013">{{cite journal|last1=Monge|first1=María Eugenia|last2=Harris|first2=Glenn A.|last3=Dwivedi|first3=Prabha|last4=Fernández|first4=Facundo M.|title=Mass Spectrometry: Recent Advances in Direct Open Air Surface Sampling/Ionization|journal=Chemical Reviews|volume=113|issue=4|year=2013|pages=2269–2308|issn=0009-2665|doi=10.1021/cr300309q|pmid=23301684}}</ref><ref name="HuangYuan2010">{{cite journal|last1=Huang|first1=Min-Zong|last2=Yuan|first2=Cheng-Hui|last3=Cheng|first3=Sy-Chyi|last4=Cho|first4=Yi-Tzu|last5=Shiea|first5=Jentaie|title=Ambient Ionization Mass Spectrometry|journal=Annual Review of Analytical Chemistry|volume=3|issue=1|year=2010|pages=43–65|issn=1936-1327|doi=10.1146/annurev.anchem.111808.073702|pmid=20636033|bibcode=2010ARAC....3...43H}}</ref> Ions can be formed by extraction into charged electrospray droplets, thermally desorbed and ionized by chemical ionization, or laser desorbed or ablated and post-ionized before they enter the mass spectrometer.<ref name="Paine 2014">{{cite journal|last1=Paine|first1=Martin R. L.|last2=Barker|first2=Philip J.|last3=Blanksby|first3=Stephen J.|title=Ambient ionisation mass spectrometry for the characterisation of polymers and polymer additives: a review|journal=Analytica Chimica Acta|date=15 January 2014|volume=808|pages=70–82|doi=10.1016/j.aca.2013.10.001|pmid=24370094|bibcode=2014AcAC..808...70P |url=https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2351&context=smhpapers}}</ref>
==Solid-liquid extraction== thumb|upright=1.3|Schematic of a DESI solid-liquid extraction ion source: primary charged droplets hit the sample surface and molecules are extracted into the liquid. Secondary charged droplets removed from the surface produce bare ions as the solvent evaporates.
Solid-liquid extraction based ambient ionization is based on the use of a charged spray, for example electrospray to create a liquid film on the sample surface.<ref name="MongeHarris2013" /><ref name="Badu-TawiahEberlin2013">{{cite journal|last1=Badu-Tawiah|first1=Abraham K.|last2=Eberlin|first2=Livia S.|last3=Ouyang|first3=Zheng|last4=Cooks|first4=R. Graham|title=Chemical Aspects of the Extractive Methods of Ambient Ionization Mass Spectrometry|journal=Annual Review of Physical Chemistry|volume=64|issue=1|year=2013|pages=481–505|issn=0066-426X|doi=10.1146/annurev-physchem-040412-110026|pmid=23331308|bibcode = 2013ARPC...64..481B }}</ref> Molecules on the surface are extracted into the solvent. The action of the primary droplets hitting the surface produces secondary droplets that are the source of ions for the mass spectrometer.
Desorption electrospray ionization (DESI) is one of the original ambient ionization sources<ref name="Takats2004">{{cite journal|last1=Takats|first1=Z.|last2=Wiseman|first2=J. M.|last3=Gologan|first3=B|last4=Cooks|first4=R. G.|title=Mass Spectrometry Sampling Under Ambient Conditions with Desorption Electrospray Ionization|journal=Science|volume=306|issue=5695|year=2004|pages=471–473|issn=0036-8075|doi=10.1126/science.1104404|pmid=15486296|bibcode = 2004Sci...306..471T |s2cid=22994482 }}</ref> and 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.<ref name="pmid16237663">{{cite journal |vauthors=Takáts Z, Wiseman JM, Cooks RG |title=Ambient mass spectrometry using desorption electrospray ionization (DESI): instrumentation, mechanisms and applications in forensics, chemistry, and biology |journal=Journal of Mass Spectrometry |volume=40 |issue=10 |pages=1261–75 |year=2005 |pmid=16237663 |doi=10.1002/jms.922 |bibcode=2005JMSp...40.1261T |doi-access=free }}</ref>
Desorption atmospheric pressure photoionization (DAPPI) is a solid-liquid extraction ambient ionization method that enables the 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.<ref>{{cite journal |vauthors=Haapala M, Pól J, Saarela V, Arvola V, Kotiaho T, Ketola RA, Franssila S, Kauppila TJ, Kostiainen R |title=Desorption Atmospheric Pressure Photoionization |journal=Anal. Chem. |volume=79 |issue=20 |pages=7867–7872 |year=2007 |doi=10.1021/ac071152g |pmid=17803282 }}</ref>
==Plasma-based techniques== Plasma-based ambient ionization is based on an electrical discharge in a flowing gas that produces metastable atoms and molecules and reactive ions. Heat is often used to assist in the desorption of volatile species from the sample. Ions are formed by chemical ionization in the gas phase.
One proposed mechanism involves Penning ionization of ambient water clusters in a helium discharge:
:<chem>He^\ast{} + [(H2O)_\mathit{n}H] ->{} [(H2O)_{\mathit n-1}H]+{} + OH^.{} + e^- </chem>.
The protonated water clusters can then protonate the sample molecules via
:<chem>[(H2O)_\mathit{n}H]+{} + M ->{} [M{} + H]+{} + \mathit{n}H2O</chem>.
For this ionization pathway, the gas-phase acidity of the protonated water clusters and the gas-phase basicity of the analyte molecule are of crucial importance. However, since especially smaller protonated water clusters with ''n'' = 1,2,3... exhibit very high gas-phase acidities, even compounds with a rather low gas-phase basicity are readily ionized by proton transfer, yielding [M+H]<sup>+</sup> quasimolecular ions.<ref name=":0">{{Cite journal|title = Characterization of Direct-Current Atmospheric-Pressure Discharges Useful for Ambient Desorption/Ionization Mass Spectrometry|journal = Journal of the American Society for Mass Spectrometry|date = 2009-05-01|pages = 837–844|volume = 20|issue = 5|doi = 10.1016/j.jasms.2008.12.020|pmid = 19185515|first1 = Jacob T.|last1 = Shelley|first2 = Joshua S.|last2 = Wiley|first3 = George C. Y.|last3 = Chan|first4 = Gregory D.|last4 = Schilling|first5 = Steven J.|last5 = Ray|first6 = Gary M.|last6 = Hieftje|doi-access = free}}</ref><ref name=":1">{{Cite journal|title = Critical assessment of ionization patterns and applications of ambient desorption/ionization mass spectrometry using FAPA–MS|journal = Journal of Mass Spectrometry|date = 2016-02-01|issn = 1096-9888|pages = 141–149|volume = 51|issue = 2|doi = 10.1002/jms.3733|pmid = 26889930|language = en|first1 = Martin|last1 = Brüggemann|first2 = Einar|last2 = Karu|first3 = Thorsten|last3 = Hoffmann|bibcode = 2016JMSp...51..141B}}</ref>
Besides protonated water clusters, other positively charged reagent ions, such as NO<sup>+</sup>, O<sub>2</sub><sup>+</sup>, NO<sub>2</sub><sup>+</sup> and CO<sub>2</sub><sup>+</sup>, may be formed in the afterglow region.<ref name=":0" /><ref name=":1" /><ref name="AndradeShelley2008" /><ref name=":2">{{Cite journal|title = Direct analysis in real time—a critical review on DART-MS|journal = Analytical and Bioanalytical Chemistry|date = 2013-09-15|issn = 1618-2642|pages = 63–80|volume = 406|issue = 1|doi = 10.1007/s00216-013-7316-0|pmid = 24036523|language = en|first = Jürgen H.|last = Gross| s2cid=9565130 }}</ref> These additional reagent ions are capable of ionizing compounds via charge-transfer processes and, thus, offer alternative routes of ionization besides proton transfer, leading to a broader range of suitable analytes. Nevertheless, these ionization mechanisms may also lead to the formation of adducts and oxidation of the original analyte compounds.<ref name=":1" />
Although most applications focus on the detection of positive ions, measurements in the negative mode are for most of the plasma-based ion sources also possible. In this case, reagent ions, such as O<sub>2</sub><sup>–</sup>, can deprotonate the analyte molecules to give [M–H]<sup>–</sup> quasimolecular ions, or form adducts with species such as NO<sub>3</sub><sup>–</sup>, yielding [M+NO<sub>3</sub>]<sup>–</sup> ions.<ref name=":1" /><ref name=":2" /> Measurements in the negative ion mode are especially favorable when the analyte molecules exhibit a high gas-phase acidity, as it is the case e.g. for carboxylic acids.thumb|upright=1.75|A direct analysis in real time (DART) metastable ion source for plasma based ambient ionization.
One of the most used plasma-based techniques for ambient ionization is probably Direct analysis in real time (DART), since it is commercially available. 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.<ref>{{cite journal |author=R.B. Cody |author2=J.A. Laramée |author3=H.D. Durst |journal=Anal. Chem. |year=2005 |volume=77 |issue=8 |pages=2297–2302 |pmid=15828760 |doi=10.1021/ac050162j |title=Versatile New Ion Source for the Analysis of Materials in Open Air under Ambient Conditions |url=https://figshare.com/articles/journal_contribution/3290839/files/5128576.pdf }}</ref>
==Laser assisted== thumb|Ion source for ambient mass spectrometry employing a combination of laser desorption and electrospray. The sample target is on the left.
Laser-based ambient ionization is a two-step process in which a pulsed laser is used to desorb or ablate material from a sample and the plume of material interacts with an electrospray or plasma to create ions. Lasers with ultraviolet and infrared wavelengths and nanosecond to femtosecond pulse widths have been used. Although atmospheric pressure MALDI is performed under ambient conditions,<ref name="LaikoBaldwin2000">{{cite journal|last1=Laiko|first1=Victor V.|last2=Baldwin|first2=Michael A.|last3=Burlingame|first3=Alma L.|title=Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry|journal=Analytical Chemistry|volume=72|issue=4|year=2000|pages=652–657|issn=0003-2700|doi=10.1021/ac990998k|pmid=10701247}}</ref> it is not generally considered to be an ambient mass spectrometry technique.<ref name="IfaWu2010">{{cite journal|last1=Ifa|first1=Demian R.|last2=Wu|first2=Chunping|last3=Ouyang|first3=Zheng|last4=Cooks|first4=R. Graham|title=Desorption electrospray ionization and other ambient ionization methods: current progress and preview|journal=The Analyst|volume=135|issue=4|year=2010|pages=669–81|issn=0003-2654|doi=10.1039/b925257f|pmid=20309441|bibcode = 2010Ana...135..669I }}</ref><ref name="WuDill2013">{{cite journal|last1=Wu|first1=Chunping|last2=Dill|first2=Allison L.|last3=Eberlin|first3=Livia S.|last4=Cooks|first4=R. Graham|last5=Ifa|first5=Demian R.|title=Mass spectrometry imaging under ambient conditions|journal=Mass Spectrometry Reviews|volume=32|issue=3|year=2013|pages=218–243|issn=0277-7037|doi=10.1002/mas.21360|pmid=22996621|pmc=3530640|bibcode=2013MSRv...32..218W}}</ref>
Laser ablation was first coupled with mass spectrometry in the 1980s for the analysis of metals using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS).<ref name="Gray1985">{{cite journal|last1=Gray|first1=Alan L.|title=Solid sample introduction by laser ablation for inductively coupled plasma source mass spectrometry|journal=The Analyst|volume=110|issue=5|year=1985|page=551|issn=0003-2654|doi=10.1039/an9851000551|bibcode = 1985Ana...110..551G }}</ref> The laser ablates the sample material that is introduced into an ICP to create atomic ions. thumb|upright=1.3|Probe electrospray ionization schematic
Infrared laser desorption can be coupled with atmospheric pressure chemical ionization using laser desorption atmospheric pressure chemical ionization (LD-APCI).<ref name="CoonMcHale2002">{{cite journal|last1=Coon|first1=Joshua J.|last2=McHale|first2=Kevin J.|last3=Harrison|first3=W. W.|title=Atmospheric pressure laser desorption/chemical ionization mass spectrometry: a new ionization method based on existing themes|journal=Rapid Communications in Mass Spectrometry|volume=16|issue=7|year=2002|pages=681–685|issn=0951-4198|doi=10.1002/rcm.626|pmid=11921247|bibcode=2002RCMS...16..681C}}</ref> For ambient ionization with a spray, the sample material is deposited on a target near the spray. The laser desorbs or ablates material from the sample that is ejected from the surface and into the spray, which can be an APCI spray with a corona discharge or an electrospray. Ambient ionization by electrospray-assisted laser desorption/ionization (ELDI) can be accomplished with ultraviolet<ref name="pmid16299699">{{cite journal |vauthors=Shiea J, Huang MZ, Hsu HJ, Lee CY, Yuan CH, Beech I, Sunner J |title=Electrospray-assisted laser desorption/ionization mass spectrometry for direct ambient analysis of solids |journal=Rapid Commun. Mass Spectrom. |volume=19 |issue=24 |pages=3701–4 |year=2005 |pmid=16299699 |doi=10.1002/rcm.2243 |bibcode=2005RCMS...19.3701S }}</ref> and infrared lasers<ref name="Peng2010">{{cite journal|last1=Peng|first1=Ivory X.|last2=Ogorzalek Loo|first2=Rachel R.|last3=Margalith|first3=Eli|last4=Little|first4=Mark W.|last5=Loo|first5=Joseph A.|title=Electrospray-assisted laser desorption ionization mass spectrometry (ELDI-MS) with an infrared laser for characterizing peptides and proteins|journal=The Analyst|volume=135|issue=4|year=2010|pages=767–72|issn=0003-2654|doi=10.1039/b923303b|pmid=20349541|bibcode = 2010Ana...135..767P|pmc=3006438}}</ref> to the desorb material into the electrospray plume. Similar approaches to laser desorption/ablation into an electrospray are matrix-assisted laser desorption electrospray ionization (MALDESI),<ref name="pmid16952462">{{cite journal |vauthors=Sampson JS, Hawkridge AM, Muddiman DC |title=Generation and detection of multiply-charged peptides and proteins by matrix-assisted laser desorption electrospray ionization (MALDESI) Fourier transform ion cyclotron resonance mass spectrometry |journal=J. Am. Soc. Mass Spectrom. |volume=17 |issue=12 |pages=1712–6 |year=2006 |pmid=16952462 |doi=10.1016/j.jasms.2006.08.003 |doi-access=free }}</ref> laser ablation electrospray ionization (LAESI),<ref name="pmid17900146">{{cite journal |vauthors=Nemes P, Vertes A |title=Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass Spectrometry |journal= Analytical Chemistry|volume= 79|issue= 21|pages= 8098–106|year=2007 |pmid=17900146 |doi=10.1021/ac071181r }}</ref> laser assisted desorption electrospray ionization (LADESI),<ref name="RezenomDong2008" /> laser desorption electrospray ionization (LDESI),<ref name="SampsonMuddiman2009">{{cite journal|last1=Sampson|first1=Jason S.|last2=Muddiman|first2=David C.|title=Atmospheric pressure infrared (10.6 μm) laser desorption electrospray ionization (IR-LDESI) coupled to a LTQ Fourier transform ion cyclotron resonance mass spectrometer|journal=Rapid Communications in Mass Spectrometry|volume=23|issue=13|year=2009|pages=1989–1992|issn=0951-4198|doi=10.1002/rcm.4113|pmid=19504481}}</ref><ref name="BerishaDold2014">{{cite journal|last1=Berisha|first1=Arton|last2=Dold|first2=Sebastian|last3=Guenther|first3=Sabine|last4=Desbenoit|first4=Nicolas|last5=Takats|first5=Zoltan|last6=Spengler|first6=Bernhard|last7=Römpp|first7=Andreas|title=A comprehensive high-resolution mass spectrometry approach for characterization of metabolites by combination of ambient ionization, chromatography and imaging methods|journal=Rapid Communications in Mass Spectrometry|volume=28|issue=16|year=2014|pages=1779–1791|issn=0951-4198|doi=10.1002/rcm.6960|pmid=25559448|bibcode=2014RCMS...28.1779B }}</ref> laser ablation mass spectrometry (LAMS),<ref name="JorabchiSmith2009">{{cite journal|last1=Jorabchi|first1=Kaveh|last2=Smith|first2=Lloyd M.|title=Single Droplet Separations and Surface Partition Coefficient Measurements Using Laser Ablation Mass Spectrometry|journal=Analytical Chemistry|volume=81|issue=23|year=2009|pages=9682–9688|issn=0003-2700|doi=10.1021/ac901819r|pmid=19886638|pmc=2911232}}</ref> and laser desorption spray post-ionization (LDSPI).<ref name="LiuQiu2010">{{cite journal|last1=Liu|first1=Jia|last2=Qiu|first2=Bo|last3=Luo|first3=Hai|title=Fingerprinting of yogurt products by laser desorption spray post-ionization mass spectrometry|journal=Rapid Communications in Mass Spectrometry|volume=24|issue=9|year=2010|pages=1365–1370|issn=0951-4198|doi=10.1002/rcm.4527|pmid=20391610|bibcode=2010RCMS...24.1365L}}</ref> The term laser electrospray mass spectrometry has been used to denote the use of a femtosecond laser for ablation.<ref name="Flanigan">{{cite journal |title=Ambient Femtosecond Laser Vaporization and Nanosecond Laser Desorption Electrospray Ionization Mass Spectrometry |journal=Annual Review of Analytical Chemistry |year=2014 |last1=Flanigan |first1=P. |last2=Levis |first2=R. |volume=7 |pages=229–256 |doi=10.1146/annurev-anchem-071213-020343 |pmid=25014343 |bibcode = 2014ARAC....7..229F }}</ref><ref name="BradyJudge2009">{{cite journal|last1=Brady|first1=John J.|last2=Judge|first2=Elizabeth J.|last3=Levis|first3=Robert J.|title=Mass spectrometry of intact neutral macromolecules using intense non-resonant femtosecond laser vaporization with electrospray post-ionization|journal=Rapid Communications in Mass Spectrometry|volume=23|issue=19|year=2009|pages=3151–3157|issn=0951-4198|doi=10.1002/rcm.4226|pmid=19714710|bibcode=2009RCMS...23.3151B}}</ref> Laser ablation into an electrospray produces highly charged ions that are similar to those observed in direct electrospray.
An alternative ionization approach following laser desorption is a plasma. UV laser ablation can be combined with a flowing afterglow plasma for mass spectrometry imaging of small molecules.<ref name="ShelleyRay2008" /> and IR desorption has been combined with a metastable ion source.<ref name="GalhenaHarris2010" />
==Two step non-laser== In two-step non-laser methods, the material removal from the sample and the ionization steps are separate.
Probe electrospray ionization (PESI) is a modified version of conventional electrospray ionization in which the capillary for sample solution transferring is replaced by a solid needle with a sharp tip.<ref>PESI was first introduced by Kenzo Hiraoka et al. in 2007 — {{cite journal |author1=Hiraoka K. |author2=Nishidate K. |author3=Mori K. |author4=Asakawa D. |author5=Suzuki S. | title = Development of probe electrospray using a solid needle | journal = Rapid Communications in Mass Spectrometry | year = 2007| volume = 21 | pages = 3139–3144 | doi = 10.1002/rcm.3201 | pmid=17708527 | issue = 18 | bibcode = 2007RCMS...21.3139H}}</ref> Compared with conventional electrospray ionization, high salt tolerance, direct sampling, and low sample consumption are found with PESI. PESI is not a continuous process; the needle for sampling and spraying is driven up and down at a frequency of 3–5 Hz.
== Vapor-ion, charge transfer reaction == The analytes are in the vapor phase. This includes breath, odors, VOCs, and other molecules with low volatility that, due to the constant improvements in sensitivity, are detectable in the vapor phase despite their low vapor pressure. Analyte ions are produced via gas-phase chemical reactions, where charging agents collide with the analyte molecules and transfer their charge. In secondary electro-spray ionization (SESI), a nano-electrospray operated at high temperature produces nanodroplets that evaporate very rapidly to produce ions and protonated water clusters that ionize the vapors of interest. SESI is commonly used for the analysis of trace concentrations of vapors being able to detect low volatility species in the gas phase with molecular masses of up to 700 Da.
==Table of techniques== In the table below, ambient ionization techniques are classified in the categories "extraction" (a solid or liquid extraction processes dynamically followed by spray or chemical ionization), "plasma" (thermal or chemical desorption with chemical ionization), "two step" (desorption or ablation followed by ionization), "laser" (laser desorption or ablation followed by ionization), "acoustic" (acoustic desorption followed by ionization), multimode (involving two of the above modes), other (techniques that do not fit into the other categories).<ref name="MongeHarris2013" />
:{|class="wikitable sortable" width="75%" ! align="left"| Acronym ! align="left" |Technique ! align="left" |Classification
|- |AFAI<ref name="HeTang2011">{{cite journal|last1=He|first1=Jiuming|last2=Tang|first2=Fei|last3=Luo|first3=Zhigang|last4=Chen|first4=Yi|last5=Xu|first5=Jing|last6=Zhang|first6=Ruiping|last7=Wang|first7=Xiaohao|last8=Abliz|first8=Zeper|title=Air flow assisted ionization for remote sampling of ambient mass spectrometry and its application|journal=Rapid Communications in Mass Spectrometry|volume=25|issue=7|year=2011|pages=843–850|issn=0951-4198|doi=10.1002/rcm.4920|pmid=21416520|bibcode=2011RCMS...25..843H }}</ref> |Air flow-assisted ionization |Extraction
|- |AFADESI<ref name="LuoHe2013">{{cite journal|last1=Luo|first1=Zhigang|last2=He|first2=Jiuming|last3=Chen|first3=Yi|last4=He|first4=Jingjing|last5=Gong|first5=Tao|last6=Tang|first6=Fei|last7=Wang|first7=Xiaohao|last8=Zhang|first8=Ruiping|last9=Huang|first9=Lan|last10=Zhang|first10=Lianfeng|last11=Lv|first11=Haining|last12=Ma|first12=Shuanggang|last13=Fu|first13=Zhaodi|last14=Chen|first14=Xiaoguang|last15=Yu|first15=Shishan|last16=Abliz|first16=Zeper|title=Air Flow-Assisted Ionization Imaging Mass Spectrometry Method for Easy Whole-Body Molecular Imaging under Ambient Conditions|journal=Analytical Chemistry|volume=85|issue=5|year=2013|pages=2977–2982|issn=0003-2700|doi=10.1021/ac400009s|pmid=23384246|doi-access=free}}</ref> |Air flow-assisted desorption electrospray ionization |Extraction
|- |APGDDI<ref name="JecklinGamez2008">{{cite journal|last1=Jecklin|first1=Matthias Conradin|last2=Gamez|first2=Gerardo|last3=Touboul|first3=David|last4=Zenobi|first4=Renato|title=Atmospheric pressure glow discharge desorption mass spectrometry for rapid screening of pesticides in food|journal=Rapid Communications in Mass Spectrometry|volume=22|issue=18|year=2008|pages=2791–2798|issn=0951-4198|doi=10.1002/rcm.3677|pmid=18697232|bibcode=2008RCMS...22.2791J}}</ref> |Atmospheric pressure glow discharge desorption ionization |Plasma
|- |APPIS<ref name="NeidholdtBeauchamp2007">{{cite journal|last1=Neidholdt|first1=Evan L.|last2=Beauchamp|first2=J. L.|title=Compact Ambient Pressure Pyroelectric Ion Source for Mass Spectrometry|journal=Analytical Chemistry|volume=79|issue=10|year=2007|pages=3945–3948|issn=0003-2700|doi=10.1021/ac070261s|pmid=17432828}}</ref> |Ambient pressure pyroelectric ion source | |- |APTDCI<ref name="CorsoD'Apolito2011">{{cite journal|last1=Corso|first1=Gaetano|last2=D'Apolito|first2=Oceania|last3=Garofalo|first3=Daniela|last4=Paglia|first4=Giuseppe|last5=Dello Russo|first5=Antonio|title=Profiling of acylcarnitines and sterols from dried blood or plasma spot by atmospheric pressure thermal desorption chemical ionization (APTDCI) tandem mass spectrometry|journal=Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids|volume=1811|issue=11|year=2011|pages=669–679|issn=1388-1981|doi=10.1016/j.bbalip.2011.05.009|pmid=21683155}}</ref> |Atmospheric pressure thermal desorption chemical ionization |Two-step
|- |APTDI<ref name="ChenOuyang2006">{{cite journal|last1=Chen|first1=Hao|last2=Ouyang|first2=Zheng|last3=Cooks|first3=R. Graham|title=Thermal Production and Reactions of Organic Ions at Atmospheric Pressure|journal=Angewandte Chemie International Edition|volume=45|issue=22|year=2006|pages=3656–3660|issn=1433-7851|doi=10.1002/anie.200600660|pmid=16639755}}</ref> |Atmospheric pressure thermal desorption/ionization |Plasma
|- |ASAP<ref name="McEwenMcKay2005">{{cite journal|last1=McEwen|first1=Charles N.|last2=McKay|first2=Richard G.|last3=Larsen|first3=Barbara S.|title=Analysis of Solids, Liquids, and Biological Tissues Using Solids Probe Introduction at Atmospheric Pressure on Commercial LC/MS Instruments|journal=Analytical Chemistry|volume=77|issue=23|year=2005|pages=7826–7831|issn=0003-2700|doi=10.1021/ac051470k|pmid=16316194}}</ref> |Atmospheric pressure solids analysis probe |Plasma
|- |BADCI<ref name="SteebGalhena2009">{{cite journal|last1=Steeb|first1=Jennifer|last2=Galhena|first2=Asiri S.|last3=Nyadong|first3=Leonard|last4=Janata|first4=Jiří|last5=Fernández|first5=Facundo M.|title=Beta electron-assisted direct chemical ionization (BADCI) probe for ambient mass spectrometry|journal=Chemical Communications|issue=31|year=2009|pages=4699–701|issn=1359-7345|doi=10.1039/b909072j|pmid=19641814}}</ref> |Beta electron-assisted direct chemical ionization |Two step
|- |CALDI<ref name="JorabchiWestphall2008">{{cite journal|last1=Jorabchi|first1=Kaveh|last2=Westphall|first2=Michael S.|last3=Smith|first3=Lloyd M.|title=Charge Assisted Laser Desorption/Ionization Mass Spectrometry of Droplets|journal=Journal of the American Society for Mass Spectrometry|volume=19|issue=6|year=2008|pages=833–840|issn=1044-0305|doi=10.1016/j.jasms.2008.02.012|pmid=18387311|pmc=2488387}}</ref> |Charge assisted laser desorption/ionization |Laser
|- |DAPCI<ref name="TakatsCotte-Rodriguez2005">{{cite journal|last1=Takats|first1=Zoltan|last2=Cotte-Rodriguez|first2=Ismael|last3=Talaty|first3=Nari|last4=Chen|first4=Huanwen|last5=Cooks|first5=R. Graham|title=Direct, trace level detection of explosives on ambient surfaces by desorption electrospray ionization mass spectrometry|journal=Chemical Communications|issue=15|year=2005|pages=1950–1952|issn=1359-7345|doi=10.1039/b418697d|pmid=15834468}}</ref> |Desorption atmospheric pressure chemical ionization |Plasma
|- |DAPPI<ref name="HaapalaPól2007">{{cite journal|last1=Haapala|first1=Markus|last2=Pól|first2=Jaroslav|last3=Saarela|first3=Ville|last4=Arvola|first4=Ville|last5=Kotiaho|first5=Tapio|last6=Ketola|first6=Raimo A.|last7=Franssila|first7=Sami|last8=Kauppila|first8=Tiina J.|last9=Kostiainen|first9=Risto|title=Desorption Atmospheric Pressure Photoionization|journal=Analytical Chemistry|volume=79|issue=20|year=2007|pages=7867–7872|issn=0003-2700|doi=10.1021/ac071152g|pmid=17803282}}</ref> |Desorption atmospheric pressure photoionization |Extraction
|- |DART<ref name="CodyLaramée2005">{{cite journal|last1=Cody|first1=Robert B.|last2=Laramée|first2=James A.|last3=Durst|first3=H. Dupont|title=Versatile New Ion Source for the Analysis of Materials in Open Air under Ambient Conditions|journal=Analytical Chemistry|volume=77|issue=8|year=2005|pages=2297–2302|issn=0003-2700|doi=10.1021/ac050162j|pmid=15828760}}</ref> |Direct analysis in real time |Plasma
|- |DBDI<ref name="NaZhao2007">{{cite journal|last1=Na|first1=Na|last2=Zhao|first2=Mengxia|last3=Zhang|first3=Sichun|last4=Yang|first4=Chengdui|last5=Zhang|first5=Xinrong|title=Development of a dielectric barrier discharge ion source for ambient mass spectrometry|journal=Journal of the American Society for Mass Spectrometry|volume=18|issue=10|year=2007|pages=1859–1862|issn=1044-0305|doi=10.1016/j.jasms.2007.07.027|pmid=17728138|doi-access=free}}</ref> |Dielectric barrier discharge ionization |Plasma
|- |DCBI<ref name="NaZhao2007" /> |Desorption corona beam ionization |Plasma
|- |DCI |Desorption chemical ionization |Plasma
|- |DEFFI<ref name="ForbesBrewer2013">{{cite journal|last1=Forbes|first1=Thomas P.|last2=Brewer|first2=Tim M.|last3=Gillen|first3=Greg|title=Desorption electro-flow focusing ionization of explosives and narcotics for ambient pressure mass spectrometry|journal=The Analyst|volume=138|issue=19|year=2013|pages=5665–73|issn=0003-2654|doi=10.1039/c3an01164j|pmid=23923127|bibcode = 2013Ana...138.5665F }}</ref> |Desorption electro-flow focusing ionization |Extraction
|- |DEMI<ref name="NyadongGalhena2009">{{cite journal|last1=Nyadong|first1=Leonard|last2=Galhena|first2=Asiri S.|last3=Fernández|first3=Facundo M.|title=Desorption Electrospray/Metastable-Induced Ionization: A Flexible Multimode Ambient Ion Generation Technique|journal=Analytical Chemistry|volume=81|issue=18|year=2009|pages=7788–7794|issn=0003-2700|doi=10.1021/ac9014098|pmid=19689156}}</ref> |Desorption electrospray/metastable-induced ionization |Multimode
|- |DESI<ref name="Takats2004" /> |Desorption electrospray ionization |Extraction
|- |DeSSI<ref name="HaddadSparrapan2006">{{cite journal|last1=Haddad|first1=Renato|last2=Sparrapan|first2=Regina|last3=Eberlin|first3=Marcos N.|title=Desorption sonic spray ionization for (high) voltage-free ambient mass spectrometry|journal=Rapid Communications in Mass Spectrometry|volume=20|issue=19|year=2006|pages=2901–2905|issn=0951-4198|doi=10.1002/rcm.2680|pmid=16941547|bibcode=2006RCMS...20.2901H}}</ref> |Desorption sonic spray ionization |Extraction
|- |DICE<ref name="ChanBolgar2010">{{cite journal|last1=Chan|first1=Chang-Ching|last2=Bolgar|first2=Mark S.|last3=Miller|first3=Scott A.|last4=Attygalle|first4=Athula B.|title=Desorption ionization by charge exchange (DICE) for sample analysis under ambient conditions by mass spectrometry|journal=Journal of the American Society for Mass Spectrometry|volume=21|issue=9|year=2010|pages=1554–1560|issn=1044-0305|doi=10.1016/j.jasms.2010.04.020|pmid=20542709|doi-access=free}}</ref> |Desorption ionization by charge exchange |Extraction
|- |DIP-APCI<ref name="KriegerHayen2013">{{cite journal|last1=Krieger|first1=Sonja|last2=Hayen|first2=Heiko|last3=Schmitz|first3=Oliver J.|title=Quantification of coumarin in cinnamon and woodruff beverages using DIP-APCI-MS and LC-MS|journal=Analytical and Bioanalytical Chemistry|volume=405|issue=25|year=2013|pages=8337–8345|issn=1618-2642|doi=10.1007/s00216-013-7238-x|pmid=23912829|s2cid=10841740 }}</ref> |Direct inlet probe–atmospheric-pressure chemical ionization |Two-step
|- |DPESI<ref name="JengLin2005">{{cite journal|last1=Jeng|first1=Jingyueh|last2=Lin|first2=Che-Hsin|last3=Shiea|first3=Jentaie|title=Electrospray from Nanostructured Tungsten Oxide Surfaces with Ultralow Sample Volume|journal=Analytical Chemistry|volume=77|issue=24|year=2005|pages=8170–8173|issn=0003-2700|doi=10.1021/ac0512960|pmid=16351172}}</ref> |Direct probe electrospray ionization | |- |EADESI<ref name="ÖzdemirChen2010">{{cite journal|last1=Özdemir|first1=Abdil|last2=Chen|first2=Chung-Hsuan|title=Electrode-assisted desorption electrospray ionization mass spectrometry|journal=Journal of Mass Spectrometry|volume=45|issue=10|year=2010|pages=1203–1211|issn=1076-5174|doi=10.1002/jms.1815|pmid=20857387|bibcode=2010JMSp...45.1203O}}</ref> |Electrode-assisted desorption electrospray ionization |Extraction
|- |EASI<ref name="HaddadSparrapan2008">{{cite journal|last1=Haddad|first1=Renato|last2=Sparrapan|first2=Regina|last3=Kotiaho|first3=Tapio|last4=Eberlin|first4=Marcos N.|title=Easy Ambient Sonic-Spray Ionization-Membrane Interface Mass Spectrometry for Direct Analysis of Solution Constituents|journal=Analytical Chemistry|volume=80|issue=3|year=2008|pages=898–903|issn=0003-2700|doi=10.1021/ac701960q|pmid=18179250}}</ref> |Easy ambient sonic-spray ionization |Extraction
|- |EESI<ref name="ChenVenter2006">{{cite journal|last1=Chen|first1=Huanwen|last2=Venter|first2=Andre|last3=Cooks|first3=R. Graham|title=Extractive electrospray ionization for direct analysis of undiluted urine, milk and other complex mixtures without sample preparation|journal=Chemical Communications|issue=19|year=2006|pages=2042–4|issn=1359-7345|doi=10.1039/b602614a|pmid=16767269}}</ref> |Extractive electrospray ionization |Two step
|- |ELDI<ref name="HuangHsu2007">{{cite journal|last1=Huang|first1=Min-Zong|last2=Hsu|first2=Hsiu-Jung|last3=Wu|first3=Chen-I|last4=Lin|first4=Shu-Yao|last5=Ma|first5=Ya-Lin|last6=Cheng|first6=Tian-Lu|last7=Shiea|first7=Jentaie|title=Characterization of the chemical components on the surface of different solids with electrospray-assisted laser desorption ionization mass spectrometry|journal=Rapid Communications in Mass Spectrometry|volume=21|issue=11|year=2007|pages=1767–1775|issn=0951-4198|doi=10.1002/rcm.3011|pmid=17479981|bibcode=2007RCMS...21.1767H}}</ref> |Electrospray laser desorption ionization |Laser
|- |ESA-Py<ref name="HsuKuo2005">{{cite journal|last1=Hsu|first1=Hsiu-Jung|last2=Kuo|first2=Tseng-Long|last3=Wu|first3=Shu-Huey|last4=Oung|first4=Jung-Nan|last5=Shiea|first5=Jentaie|title=Characterization of Synthetic Polymers by Electrospray-Assisted Pyrolysis Ionization-Mass Spectrometry|journal=Analytical Chemistry|volume=77|issue=23|year=2005|pages=7744–7749|issn=0003-2700|doi=10.1021/ac051116m|pmid=16316184}}</ref> |Electrospray-assisted pyrolysis ionization |Spray
|- |ESTASI<ref name="QiaoTobolkina2014">{{cite journal|last1=Qiao|first1=Liang|last2=Tobolkina|first2=Elena|last3=Lesch|first3=Andreas|last4=Bondarenko|first4=Alexandra|last5=Zhong|first5=Xiaoqin|last6=Liu|first6=Baohong|last7=Pick|first7=Horst|last8=Vogel|first8=Horst|last9=Girault|first9=Hubert H.|title=Electrostatic Spray Ionization Mass Spectrometry Imaging|journal=Analytical Chemistry|volume=86|issue=4|year=2014|pages=2033–2041|issn=0003-2700|doi=10.1021/ac4031779|pmid=24446793|url=http://infoscience.epfl.ch/record/196242}}</ref> |Electrostatic spray ionization |Extraction
|- |FAPA<ref name="AndradeShelley2008">{{cite journal|last1=Andrade|first1=Francisco J.|last2=Shelley|first2=Jacob T.|last3=Wetzel|first3=William C.|last4=Webb|first4=Michael R.|last5=Gamez|first5=Gerardo|last6=Ray|first6=Steven J.|last7=Hieftje|first7=Gary M.|title=Atmospheric Pressure Chemical Ionization Source. 1. Ionization of Compounds in the Gas Phase|journal=Analytical Chemistry|volume=80|issue=8|year=2008|pages=2646–2653|issn=0003-2700|doi=10.1021/ac800156y|pmid=18345693}}</ref> |Flowing atmospheric pressure afterglow |Plasma
|- |FIDI<ref name="GrimmBeauchamp2003">{{cite journal|last1=Grimm|first1=Ronald L.|last2=Beauchamp|first2=J. L.|title=Field-Induced Droplet Ionization Mass Spectrometry|journal=The Journal of Physical Chemistry B|volume=107|issue=51|year=2003|pages=14161–14163|issn=1520-6106|doi=10.1021/jp037099r}}</ref> |Field-induced droplet ionization | |- |HALDI<ref name="RenLiu2013">{{cite journal|last1=Ren|first1=Xinxin|last2=Liu|first2=Jia|last3=Zhang|first3=Chengsen|last4=Luo|first4=Hai|title=Direct analysis of samples under ambient condition by high-voltage-assisted laser desorption ionization mass spectrometry in both positive and negative ion mode|journal=Rapid Communications in Mass Spectrometry|volume=27|issue=5|year=2013|pages=613–620|issn=0951-4198|doi=10.1002/rcm.6499|pmid=23413220|bibcode=2013RCMS...27..613R}}</ref> |High-voltage-assisted laser desorption ionization |Laser
|- |HAPGDI<ref name="AndradeShelley2008"/> |Helium atmospheric pressure glow discharge ionization |Plasma
|- |IR-LAMICI<ref name="GalhenaHarris2010">{{cite journal|last1=Galhena|first1=Asiri S.|last2=Harris|first2=Glenn A.|last3=Nyadong|first3=Leonard|last4=Murray|first4=Kermit K.|last5=Fernández|first5=Facundo M.|title=Small Molecule Ambient Mass Spectrometry Imaging by Infrared Laser Ablation Metastable-Induced Chemical Ionization|journal=Analytical Chemistry|volume=82|issue=6|year=2010|pages=2178–2181|issn=0003-2700|doi=10.1021/ac902905v|pmid=20155978|doi-access=free}}</ref> |Infrared laser ablation metastable-induced chemical ionization |Laser
|- |JeDI<ref name="Van BerkelPasilis2008">{{cite journal|last1=Van Berkel|first1=Gary J.|last2=Pasilis|first2=Sofie P.|last3=Ovchinnikova|first3=Olga|title=Established and emerging atmospheric pressure surface sampling/ionization techniques for mass spectrometry|journal=Journal of Mass Spectrometry|volume=43|issue=9|year=2008|pages=1161–1180|issn=1076-5174|doi=10.1002/jms.1440|pmid=18671242|bibcode=2008JMSp...43.1161V}}</ref> |Jet desorption electrospray ionization |Extraction
|- |LADESI<ref name="RezenomDong2008">{{cite journal|last1=Rezenom|first1=Yohannes H.|last2=Dong|first2=Jianan|last3=Murray|first3=Kermit K.|title=Infrared laser-assisted desorption electrospray ionization mass spectrometry|journal=The Analyst|volume=133|issue=2|year=2008|pages=226–32|issn=0003-2654|doi=10.1039/b715146b|pmid=18227946|bibcode = 2008Ana...133..226R }}</ref> |Laser assisted desorption electrospray ionization |Laser
|- |LAESI<ref name="NemesVertes2007">{{cite journal|last1=Nemes|first1=Peter|last2=Vertes|first2=Akos|title=Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass Spectrometry|journal=Analytical Chemistry|volume=79|issue=21|year=2007|pages=8098–8106|issn=0003-2700|doi=10.1021/ac071181r|pmid=17900146}}</ref> |Laser ablation electrospray ionization |Laser
|- |LA-FAPA<ref name="ShelleyRay2008">{{cite journal|last1=Shelley|first1=Jacob T.|last2=Ray|first2=Steven J.|last3=Hieftje|first3=Gary M.|title=Laser Ablation Coupled to a Flowing Atmospheric Pressure Afterglow for Ambient Mass Spectral Imaging|journal=Analytical Chemistry|volume=80|issue=21|year=2008|pages=8308–8313|issn=0003-2700|doi=10.1021/ac801594u|pmid=18826246}}</ref> |Laser ablation flowing atmospheric pressure afterglow |Laser
|- |LA-ICP<ref name="JanssensGrieken2004">{{cite book|author1=K. Janssens|author2=R. Van Grieken|title=Non-destructive Micro Analysis of Cultural Heritage Materials|url=https://books.google.com/books?id=zzqxUOOgNp4C&pg=PA313|date=26 November 2004|publisher=Elsevier|isbn=978-0-08-045442-9|pages=313–}}</ref> |Laser ablation inductively coupled plasma |Laser
|- |LD-APCI<ref name="CoonMcHale2002" /> |Laser desorption atmospheric pressure chemical ionization |Laser
|- |LDTD<ref name="WuHughes2007">{{cite journal|last1=Wu|first1=Jin|last2=Hughes|first2=Christopher S.|last3=Picard|first3=Pierre|last4=Letarte|first4=Sylvain|last5=Gaudreault|first5=Mireille|last6=Lévesque|first6=Jean-François|last7=Nicoll-Griffith|first7=Deborah A.|last8=Bateman|first8=Kevin P.|title=High-Throughput Cytochrome P450 Inhibition Assays Using Laser Diode Thermal Desorption-Atmospheric Pressure Chemical Ionization-Tandem Mass Spectrometry|journal=Analytical Chemistry|volume=79|issue=12|year=2007|pages=4657–4665|issn=0003-2700|doi=10.1021/ac070221o|pmid=17497828}}</ref> |Laser diode thermal desorption |Laser
|- |LDESI<ref name="SampsonMuddiman2009" /><ref name="BerishaDold2014" /> |Laser desorption electrospray ionization |Laser
|- |LDSPI<ref name="LiuQiu2010" /> |Laser desorption spray post-ionization |Laser
|- |LEMS<ref name="BradyJudge2009" /> |Laser electrospray mass spectrometry |Laser
|- |LESA<ref>{{cite web |url=http://www.advion.com/news-events/press-releases/100930-LiquidExtractionSurfaceAnalysis-LESA/ |title=LESA – A New Mass Spectrometry-based Surface Analysis Technique Using the TriVersa NanoMate |access-date=2014-07-20 |archive-url=https://web.archive.org/web/20140727013255/http://www.advion.com/news-events/press-releases/100930-LiquidExtractionSurfaceAnalysis-LESA/ |archive-date=2014-07-27 }}</ref> |Liquid extraction surface analysis |Extraction
|- |LIAD-ESI<ref name="ChengCheng2009">{{cite journal|last1=Cheng|first1=Sy-Chyi|last2=Cheng|first2=Tain-Lu|last3=Chang|first3=Hui-Chiu|last4=Shiea|first4=Jentaie|title=Using Laser-Induced Acoustic Desorption/Electrospray Ionization Mass Spectrometry To Characterize Small Organic and Large Biological Compounds in the Solid State and in Solution Under Ambient Conditions|journal=Analytical Chemistry|volume=81|issue=3|year=2009|pages=868–874|issn=0003-2700|doi=10.1021/ac800896y|pmid=19178334}}</ref> |Laser-induced acoustic desorption-electrospray ionization |Acoustic
|- |LMJ-SSP<ref name="Van BerkelKertesz2009">{{cite journal|last1=Van Berkel|first1=Gary J.|last2=Kertesz|first2=Vilmos|last3=King|first3=Richard C.|title=High-Throughput Mode Liquid Microjunction Surface Sampling Probe|journal=Analytical Chemistry|volume=81|issue=16|year=2009|pages=7096–7101|issn=0003-2700|doi=10.1021/ac901098d|pmid=19606841}}</ref> |Liquid microjunction-surface sampling probe |Extraction
|- |LPTD<ref name="SahaChen2013">{{cite journal|last1=Saha|first1=Subhrakanti|last2=Chen|first2=Lee Chuin|last3=Mandal|first3=Mridul Kanti|last4=Hiraoka|first4=Kenzo|title=Leidenfrost Phenomenon-assisted Thermal Desorption (LPTD) and Its Application to Open Ion Sources at Atmospheric Pressure Mass Spectrometry|journal=Journal of the American Society for Mass Spectrometry|volume=24|issue=3|year=2013|pages=341–347|issn=1044-0305|doi=10.1007/s13361-012-0564-y|pmid=23423791|bibcode = 2013JASMS..24..341S |s2cid=39368022 }}</ref> |Leidenfrost phenomenon-assisted thermal desorption |Two-step
|- |LS-APGD<ref name="QuarlesCarado2011">{{cite journal|last1=Quarles|first1=C. Derrick|last2=Carado|first2=Anthony J.|last3=Barinaga|first3=Charles J.|last4=Koppenaal|first4=David W.|last5=Marcus|first5=R. Kenneth|title=Liquid sampling–atmospheric pressure glow discharge (LS-APGD) ionization source for elemental mass spectrometry: preliminary parametric evaluation and figures of merit|journal=Analytical and Bioanalytical Chemistry|volume=402|issue=1|year=2011|pages=261–268|issn=1618-2642|doi=10.1007/s00216-011-5359-7|pmid=21910014|s2cid=33571580 }}</ref>
| Liquid sampling-atmospheric pressure glow discharge |Plasma
|- |LSI<ref name="TrimpinInutan2009">{{cite journal|last1=Trimpin|first1=S.|last2=Inutan|first2=E. D.|last3=Herath|first3=T. N.|last4=McEwen|first4=C. N.|title=Laserspray Ionization, a New Atmospheric Pressure MALDI Method for Producing Highly Charged Gas-phase Ions of Peptides and Proteins Directly from Solid Solutions|journal=Molecular & Cellular Proteomics|volume=9|issue=2|year=2009|pages=362–367|issn=1535-9476|doi=10.1074/mcp.M900527-MCP200|doi-access=free |pmid=19955086|pmc=2830846}}</ref> |Laser spray ionization |Other
|- |LTP<ref name="HarperCharipar2008">{{cite journal|last1=Harper|first1=Jason D.|last2=Charipar|first2=Nicholas A.|last3=Mulligan|first3=Christopher C.|last4=Zhang|first4=Xinrong|last5=Cooks|first5=R. Graham|last6=Ouyang|first6=Zheng|title=Low-Temperature Plasma Probe for Ambient Desorption Ionization|journal=Analytical Chemistry|volume=80|issue=23|year=2008|pages=9097–9104|issn=0003-2700|doi=10.1021/ac801641a|pmid=19551980}}</ref> |Low temperature plasma |Plasma
|- |MAII<ref name="McEwenPagnotti2010">{{cite journal|last1=McEwen|first1=Charles N.|last2=Pagnotti|first2=Vincent S.|last3=Inutan|first3=Ellen D.|last4=Trimpin|first4=Sarah|title=New Paradigm in Ionization: Multiply Charged Ion Formation from a Solid Matrix without a Laser or Voltage|journal=Analytical Chemistry|volume=82|issue=22|year=2010|pages=9164–9168|issn=0003-2700|doi=10.1021/ac102339y|pmid=20973512}}</ref> |Matrix-assisted inlet ionization |Other
|- |MALDESI<ref name="SampsonHawkridge2006">{{cite journal|last1=Sampson|first1=Jason S.|last2=Hawkridge|first2=Adam M.|last3=Muddiman|first3=David C.|title=Generation and detection of multiply-charged peptides and proteins by matrix-assisted laser desorption electrospray ionization (MALDESI) fourier transform ion cyclotron resonance mass spectrometry|journal=Journal of the American Society for Mass Spectrometry|volume=17|issue=12|year=2006|pages=1712–1716|issn=1044-0305|doi=10.1016/j.jasms.2006.08.003|pmid=16952462|doi-access=free}}</ref> |Matrix-assisted laser desorption electrospray ionization |Laser
|- |MFGDP<ref name="WangDing2014">{{cite journal|last1=Wang|first1=Bo|last2=Ding|first2=Xuelu|last3=Zhao|first3=Zhongjun|last4=Duan|first4=Yixiang|title=Method development for directly screening pesticide residues in foodstuffs using ambient microfabricated glow discharge plasma (MFGDP) desorption/ionization mass spectrometry|journal=International Journal of Mass Spectrometry|year=2014|issn=1387-3806|doi=10.1016/j.ijms.2014.05.018|volume=377|pages=507–514|bibcode = 2015IJMSp.377..507W }}</ref> |Microfabricated glow discharge plasma |Plasma
|- |MIPDI<ref name="ZhanZhao2013">{{cite journal|last1=Zhan|first1=Xuefang|last2=Zhao|first2=Zhongjun|last3=Yuan|first3=Xin|last4=Wang|first4=Qihui|last5=Li|first5=Dandan|last6=Xie|first6=Hong|last7=Li|first7=Xuemei|last8=Zhou|first8=Meigui|last9=Duan|first9=Yixiang|title=Microwave-Induced Plasma Desorption/Ionization Source for Ambient Mass Spectrometry|journal=Analytical Chemistry|volume=85|issue=9|year=2013|pages=4512–4519|issn=0003-2700|doi=10.1021/ac400296v|pmid=23534913}}</ref> |microwave induced plasma desorption ionization |Plasma
|- |nano-DESI<ref name="RoachLaskin2010">{{cite journal|last1=Roach|first1=Patrick J.|last2=Laskin|first2=Julia|author2-link=Julia Laskin|last3=Laskin|first3=Alexander|title=Nanospray desorption electrospray ionization: an ambient method for liquid-extraction surface sampling in mass spectrometry|journal=The Analyst|volume=135|issue=9|year=2010|pages=2233–6|issn=0003-2654|doi=10.1039/c0an00312c|pmid=20593081|bibcode = 2010Ana...135.2233R }}</ref> |Nanospray desorption electrospray ionization |Extraction
|- |ND-EESI<ref name="ChenWortmann2007">{{cite journal|last1=Chen|first1=Huanwen|last2=Wortmann|first2=Arno|last3=Zenobi|first3=Renato|title=Neutral desorption sampling coupled to extractive electrospray ionization mass spectrometry for rapid differentiation of biosamples by metabolomic fingerprinting|journal=Journal of Mass Spectrometry|volume=42|issue=9|year=2007|pages=1123–1135|issn=1076-5174|doi=10.1002/jms.1282|pmid=17721903|bibcode=2007JMSp...42.1123C}}</ref> |Neutral desorption extractive electrospray ionization |Two step
|- |PADI<ref name="RatcliffeRutten2007">{{cite journal|last1=Ratcliffe|first1=Lucy V.|last2=Rutten|first2=Frank J. M.|last3=Barrett|first3=David A.|last4=Whitmore|first4=Terry|last5=Seymour|first5=David|last6=Greenwood|first6=Claire|last7=Aranda-Gonzalvo|first7=Yolanda|last8=Robinson|first8=Steven|last9=McCoustra|first9=Martin|title=Surface Analysis under Ambient Conditions Using Plasma-Assisted Desorption/Ionization Mass Spectrometry|journal=Analytical Chemistry|volume=79|issue=16|year=2007|pages=6094–6101|issn=0003-2700|doi=10.1021/ac070109q|pmid=17628043}}</ref> |Plasma-assisted desorption ionization |Plasma
|- |Paint Spray*<ref name="Paine 2012">{{cite journal|last1=Paine|first1=Martin R. L.|last2=Barker|first2=Philip J.|last3=Blanksby|first3=Stephen J.|title=Paint Spray Mass Spectrometry for the Detection of Additives from Polymers on Conducting Surfaces|journal=Mass Spectrometry Letters|date=2012|volume=3|issue=1|pages=25–28|doi=10.5478/MSL.2012.3.1.025|doi-access=free}}</ref> |Paint spray |Extraction
|- |PALDI<ref name="FengZhang2014">{{cite journal|last1=Feng|first1=Baosheng|last2=Zhang|first2=Jialing|last3=Chang|first3=Cuilan|last4=Li|first4=Liping|last5=Li|first5=Min|last6=Xiong|first6=Xingchuang|last7=Guo|first7=Chengan|last8=Tang|first8=Fei|last9=Bai|first9=Yu|last10=Liu|first10=Huwei|title=Ambient Mass Spectrometry Imaging: Plasma Assisted Laser Desorption Ionization Mass Spectrometry Imaging and Its Applications|journal=Analytical Chemistry|volume=86|issue=9|year=2014|pages=4164–4169|issn=0003-2700|doi=10.1021/ac403310k|pmid=24670045}}</ref> |Plasma-assisted laser desorption ionization |Laser
|- |PAMLDI<ref name="ZhangZhou2012">{{cite journal|last1=Zhang|first1=Jialing|last2=Zhou|first2=Zhigui|last3=Yang|first3=Jianwang|last4=Zhang|first4=Wei|last5=Bai|first5=Yu|last6=Liu|first6=Huwei|title=Thin Layer Chromatography/Plasma Assisted Multiwavelength Laser Desorption Ionization Mass Spectrometry for Facile Separation and Selective Identification of Low Molecular Weight Compounds|journal=Analytical Chemistry|volume=84|issue=3|year=2012|pages=1496–1503|issn=0003-2700|doi=10.1021/ac202732y|pmid=22243032}}</ref> |Plasma-assisted multiwavelength laser desorption ionization |Laser
|- |PASIT<ref name="ZhouZhang2014">{{cite journal|last1=Zhou|first1=Yueming|last2=Zhang|first2=Ning|last3=Li|first3=Yafeng|last4=Xiong|first4=Caiqiao|last5=Chen|first5=Suming|last6=Chen|first6=Yongtai|last7=Nie|first7=Zongxiu|title=Plasma-based ambient sampling/ionization/transmission integrated source for mass spectrometry|journal=The Analyst|volume=139|issue=21|pages=5387–92|year=2014|issn=0003-2654|doi=10.1039/C4AN00979G|pmid=25147876|bibcode = 2014Ana...139.5387Z }}</ref> |Plasma-based ambient sampling/ionization/transmission |Extraction
|- |PAUSI<ref name="ZhuLi2014">{{cite journal|last1=Zhu|first1=Hongying|last2=Li|first2=Gongyu|last3=Huang|first3=Guangming|title=Screening of Complicated Matrixes with Paper Assisted Ultrasonic Spray Ionization Mass Spectrometry|journal=Journal of the American Society for Mass Spectrometry|volume=25|issue=6|year=2014|pages=935–942|issn=1044-0305|doi=10.1007/s13361-014-0862-7|pmid=24664810|bibcode = 2014JASMS..25..935Z |s2cid=2521462 }}</ref> |Paper assisted ultrasonic spray ionization | |- |PESI<ref name="HiraokaNishidate2007">{{cite journal|last1=Hiraoka|first1=Kenzo|last2=Nishidate|first2=Kentaro|last3=Mori|first3=Kunihiko|last4=Asakawa|first4=Daiki|last5=Suzuki|first5=Shigeo|title=Development of probe electrospray using a solid needle|journal=Rapid Communications in Mass Spectrometry|volume=21|issue=18|year=2007|pages=3139–3144|issn=0951-4198|doi=10.1002/rcm.3201|pmid=17708527|bibcode=2007RCMS...21.3139H}}</ref> |Probe electrospray ionization |Two step
|- |PS<ref name="LiuWang2010">{{cite journal|last1=Liu|first1=Jiangjiang|last2=Wang|first2=He|last3=Manicke|first3=Nicholas E.|last4=Lin|first4=Jin-Ming|last5=Cooks|first5=R. Graham|last6=Ouyang|first6=Zheng|title=Development, Characterization, and Application of Paper Spray Ionization|journal=Analytical Chemistry|volume=82|issue=6|year=2010|pages=2463–2471|issn=0003-2700|doi=10.1021/ac902854g|pmid=20158226}}</ref> |Paper spray | |- |PTC-ESI<ref name="HuangYou2012">{{cite journal|last1=Huang|first1=Yun-Qing|last2=You|first2=Jin-Qing|last3=Yuan|first3=Bi-Feng|last4=Feng|first4=Yu-Qi|title=Sample preparation and direct electrospray ionization on a tip column for rapid mass spectrometry analysis of complex samples|journal=The Analyst|volume=137|issue=19|year=2012|pages=4593–7|issn=0003-2654|doi=10.1039/c2an35856e|pmid=22898704|bibcode = 2012Ana...137.4593H }}</ref> |Pipette tip column electrospray ionization |Extraction
|- |RADIO<ref name="DixonSampson2009">{{cite journal|last1=Dixon|first1=R. Brent|last2=Sampson|first2=Jason S.|last3=Muddiman|first3=David C.|title=Generation of multiply charged peptides and proteins by radio frequency acoustic desorption and ionization for mass spectrometric detection|journal=Journal of the American Society for Mass Spectrometry|volume=20|issue=4|year=2009|pages=597–600|issn=1044-0305|doi=10.1016/j.jasms.2008.11.024|pmid=19112029|doi-access=free}}</ref> |Radiofrequency acoustic desorption and ionization |Acoustic
|- |RASTIR<ref name="DixonSampson2008">{{cite journal|last1=Dixon|first1=R. Brent|last2=Sampson|first2=Jason S.|last3=Hawkridge|first3=Adam M.|last4=Muddiman|first4=David C.|title=Ambient Aerodynamic Ionization Source for Remote Analyte Sampling and Mass Spectrometric Analysis|journal=Analytical Chemistry|volume=80|issue=13|year=2008|pages=5266–5271|issn=0003-2700|doi=10.1021/ac800289f|pmid=18529018}}</ref> |Remote analyte sampling transport and ionization relay | |- |REIMS<ref name="SchäferDénes2009">{{cite journal|last1=Schäfer|first1=Karl-Christian|last2=Dénes|first2=Júlia|last3=Albrecht|first3=Katalin|last4=Szaniszló|first4=Tamás|last5=Balog|first5=Júlia|last6=Skoumal|first6=Réka|last7=Katona|first7=Mária|last8=Tóth|first8=Miklós|last9=Balogh|first9=Lajos|last10=Takáts|first10=Zoltán|title=In Vivo, In Situ Tissue Analysis Using Rapid Evaporative Ionization Mass Spectrometry|journal=Angewandte Chemie International Edition|volume=48|issue=44|year=2009|pages=8240–8242|issn=1433-7851|doi=10.1002/anie.200902546|pmid=19746375}}</ref> |Rapid evaporative ionization mass spectrometry |Other
|- |RoPPI<ref name="BennettMorzan2014">{{cite journal|last1=Bennett|first1=Rachel V.|last2=Morzan|first2=Ezequiel M.|last3=Huckaby|first3=Jacob O.|last4=Monge|first4=María Eugenia|last5=Christensen|first5=Henrick I.|last6=Fernández|first6=Facundo M.|title=Robotic plasma probe ionization mass spectrometry (RoPPI-MS) of non-planar surfaces|journal=The Analyst|volume=139|issue=11|year=2014|pages=2658–62|issn=0003-2654|doi=10.1039/c4an00277f|pmid=24603806|bibcode = 2014Ana...139.2658B |hdl=11336/4102 |hdl-access=free}}</ref> |Robotic plasma probe ionization |Two-step
|- |SACI<ref name="CrottiTraldi2009">{{cite journal|last1=Crotti|first1=Sara|last2=Traldi|first2=Pietro|title=Aspects of the Role of Surfaces in Ionization Processes|journal=Combinatorial Chemistry & High Throughput Screening|volume=12|issue=2|year=2009|pages=125–136|issn=1386-2073|doi=10.2174/138620709787315427|pmid=19199882}}</ref> |Surface activated chemical ionization | |- |SAII<ref name="PagnottiInutan2011">{{cite journal|last1=Pagnotti|first1=Vincent S.|last2=Inutan|first2=Ellen D.|last3=Marshall|first3=Darrell D.|last4=McEwen|first4=Charles N.|last5=Trimpin|first5=Sarah|title=Inlet Ionization: A New Highly Sensitive Approach for Liquid Chromatography/Mass Spectrometry of Small and Large Molecules|journal=Analytical Chemistry|volume=83|issue=20|year=2011|pages=7591–7594|issn=0003-2700|doi=10.1021/ac201982r|pmid=21899326}}</ref> |Solvent-assisted inlet ionization |Other
|- |SAWN<ref name="HeronWilson2010">{{cite journal|last1=Heron|first1=Scott R.|last2=Wilson|first2=Rab|last3=Shaffer|first3=Scott A.|last4=Goodlett|first4=David R.|last5=Cooper|first5=Jonathan M.|title=Surface Acoustic Wave Nebulization of Peptides As a Microfluidic Interface for Mass Spectrometry|journal=Analytical Chemistry|volume=82|issue=10|year=2010|pages=3985–3989|issn=0003-2700|doi=10.1021/ac100372c|pmid=20364823|pmc=3073871}}</ref> |Surface acoustic wave nebulization |Acoustic
|- |SESI<ref name="WuSiems2000">{{cite journal|last1=Wu|first1=Ching|last2=Siems|first2=William F.|last3=Hill|first3=Herbert H.|title=Secondary Electrospray Ionization Ion Mobility Spectrometry/Mass Spectrometry of Illicit Drugs|journal=Analytical Chemistry|volume=72|issue=2|year=2000|pages=396–403|issn=0003-2700|doi=10.1021/ac9907235|pmid=10658336}}</ref> |Secondary electrospray ionization |Vapor-ion, charge transfer |- |SPA-nanoESI<ref name="MandalYoshimura2012">{{cite journal|last1=Mandal|first1=Mridul Kanti|last2=Yoshimura|first2=Kentaro|last3=Saha|first3=Subhrakanti|last4=Ninomiya|first4=Satoshi|last5=Rahman|first5=Md. Obaidur|last6=Yu|first6=Zhan|last7=Chen|first7=Lee Chuin|last8=Shida|first8=Yasuo|last9=Takeda|first9=Sen|last10=Nonami|first10=Hiroshi|last11=Hiraoka|first11=Kenzo|title=Solid probe assisted nanoelectrospray ionization mass spectrometry for biological tissue diagnostics|journal=The Analyst|volume=137|issue=20|year=2012|pages=4658–61|issn=0003-2654|doi=10.1039/c2an36006c|pmid=22937532|bibcode = 2012Ana...137.4658M }}</ref> |Solid probe assisted nanoelectrospray ionization |Two-step
|- |SPAMS<ref name="MartinFarquar2009">{{cite journal|last1=Martin|first1=Audrey N.|last2=Farquar|first2=George R.|last3=Steele|first3=Paul T.|last4=Jones|first4=A. Daniel|last5=Frank|first5=Matthias|title=Use of Single Particle Aerosol Mass Spectrometry for the Automated Nondestructive Identification of Drugs in Multicomponent Samples|journal=Analytical Chemistry|volume=81|issue=22|year=2009|pages=9336–9342|issn=0003-2700|doi=10.1021/ac901208h|pmid=19842633}}</ref> |Single-particle aerosol mass spectrometry |Other
|- |SSI<ref name="HechtEvard2017">{{cite journal|last1=Hecht|first1=Max|last2=Evard|first2=Hanno|last3=Takkis|first3=Kalev|last4=Veigure|first4=Rūta|last5=Aro|first5=Rudolf|last6=Lohmus|first6=Rynno|last7=Herodes|first7=Koit|last8=Leito|first8=Ivo|last9=Kipper|first9=Karin|title=Sponge Spray — Reaching New Dimensions of Direct Sampling and Analysis by MS|journal=Analytical Chemistry|volume=89|issue=21|year=2017|pages=11592–11597|issn=0003-2700|doi=10.1021/acs.analchem.7b02957|pmid=29028329}}</ref> |Sponge-Spray Ionization | |- |SSP<ref name="Van BerkelSanchez2002">{{cite journal|last1=Van Berkel|first1=Gary J.|last2=Sanchez|first2=Amaury D.|last3=Quirke|first3=J. Martin E.|title=Thin-Layer Chromatography and Electrospray Mass Spectrometry Coupled Using a Surface Sampling Probe|journal=Analytical Chemistry|volume=74|issue=24|year=2002|pages=6216–6223|issn=0003-2700|doi=10.1021/ac020540+|pmid=12510741}}</ref> |Surface sampling probe |Extraction
|- |SwiFerr<ref name="NeidholdtBeauchamp2011">{{cite journal|last1=Neidholdt|first1=Evan L.|last2=Beauchamp|first2=J. L.|title=Switched Ferroelectric Plasma Ionizer (SwiFerr) for Ambient Mass Spectrometry|journal=Analytical Chemistry|volume=83|issue=1|year=2011|pages=38–43|issn=0003-2700|doi=10.1021/ac1013833|pmid=21128617}}</ref> |Switched ferroelectric plasma ionizer |Other
|- |TDAMS<ref name="LinChen2010">{{cite journal|last1=Lin|first1=Jia-Yi|last2=Chen|first2=Tsung-Yi|last3=Chen|first3=Jen-Yi|last4=Chen|first4=Yu-Chie|title=Multilayer gold nanoparticle-assisted thermal desorption ambient mass spectrometry for the analysis of small organics|journal=The Analyst|volume=135|issue=10|year=2010|pages=2668–75|issn=0003-2654|doi=10.1039/c0an00157k|pmid=20721383|bibcode = 2010Ana...135.2668L }}</ref> |Thermal desorption-based ambient mass spectrometry |Spray
|- |TM-DESI<ref name="ChipukBrodbelt2008">{{cite journal|last1=Chipuk|first1=Joseph E.|last2=Brodbelt|first2=Jennifer S.|title=Transmission mode desorption electrospray ionization|journal=Journal of the American Society for Mass Spectrometry|volume=19|issue=11|year=2008|pages=1612–1620|issn=1044-0305|doi=10.1016/j.jasms.2008.07.002|pmid=18684639|doi-access=free}}</ref> |Transmission mode desorption electrospray ionization |Extraction
|- |TS<ref name="KerianJarmusch2014">{{cite journal|last1=Kerian|first1=Kevin S.|last2=Jarmusch|first2=Alan K.|last3=Cooks|first3=R. Graham|title=Touch spray mass spectrometry for in situ analysis of complex samples|journal=The Analyst|volume=139|issue=11|year=2014|pages=2714–20|issn=0003-2654|doi=10.1039/c4an00548a|pmid=24756256|bibcode = 2014Ana...139.2714K|pmc=4063212}}</ref> |Touch spray |Two-step
|- |UASI<ref name="ChenChao2010">{{cite journal|last1=Chen|first1=Tsung-Yi|last2=Chao|first2=Chin-Sheng|last3=Mong|first3=Kwok-Kong Tony|last4=Chen|first4=Yu-Chie|title=Ultrasonication-assisted spray ionization mass spectrometry for on-line monitoring of organic reactions|journal=Chemical Communications|volume=46|issue=44|year=2010|pages=8347–9|issn=1359-7345|doi=10.1039/c0cc02629h|pmid=20957254|url=https://zenodo.org/record/999715}}</ref> |Ultrasonication-assisted spray ionization |Acoustic
|- |V-EASI<ref name="SantosRegiani2011">{{cite journal|last1=Santos|first1=Vanessa G.|last2=Regiani|first2=Thaís|last3=Dias|first3=Fernanda F. G.|author4-link=Wanderson Romão|last4=Romão|first4=Wanderson|last5=Jara|first5=Jose Luis Paz|last6=Klitzke|first6=Clécio F.|last7=Coelho|first7=Fernando|last8=Eberlin|first8=Marcos N.|title=Venturi Easy Ambient Sonic-Spray Ionization|journal=Analytical Chemistry|volume=83|issue=4|year=2011|pages=1375–1380|issn=0003-2700|doi=10.1021/ac102765z|pmid=21235233}}</ref> |Venturi easy ambient sonic-spray ionization |Extraction |- |BS <ref>{{Cite journal|last=Jen-Ying Liu, Pei-Chun Chen, Yea-Wenn Liou, Kai-Yin Chang|first=Cheng-Huang Lin|date=2017|title=Development and Application of a Brush Spray Derived from a Calligraphy Brush Style Synthetic Hair Pen for Use in ESI/MS|journal=Mass Spectrometry|volume=6|issue=Spec Iss|article-number=s0058|doi=10.5702/massspectrometry.s0058|pmc=5358408|pmid=28337397}}</ref> |Brush-Spray Ionization |Two-step |- |FS <ref>{{Cite journal|last=Yea-Wenn Liou, Jian-Siang Wang, Chien-Chung Chen and Cheng-Huang Lin|date=2017|title=Development of an on-line microextraction method for use in fiber-spray/mass spectrometry|journal=International Journal of Mass Spectrometry|volume=421|pages=178–183|doi=10.1016/j.ijms.2017.07.001|bibcode=2017IJMSp.421..178L}}</ref> |Fiber-Spray Ionization |Extraction |} (*) Not an acronym.
== Table of commercially available ambient ionization sources == {| class="wikitable" |+ !Technique !Commercial Brand !Company !Website |- |Ambient Pressure Photo Ionization (APPI) |MasCom
GC-(APPI) |MasCom Technologies GmbH |https://www.mascom-bremen.de/ | |- |Atmospheric pressure solids analysis probe (ASAP) |RADIAN |Waters, USA |https://www.waters.com/ | |- |Desorption Electrospray Ionization (DESI) |DESI2D |Prosolia Inc, Indianapolis, IN |https://prosolia.com/ | |- |Direct Analysis in Real Time (DART) |DART |IonSense Inc, Saugus, MA |https://www.ionsense.com/ | |- |Liquid Extraction Surface Analysis (LESA) |TriVersaNanoMate |Advion, Ithaca, NY |https://advion.com/ | |- |Probe Electrospray Ionization (PESI) |DPiMS-8060 |Shimadzu, Japan |https://www.shimadzu.com/ | |- |Rapid evaporative Ionization Mass Spectrometry (REIMS) |REIMS |Waters, USA |https://www.waters.com/ | |- |Secondary Electrospray Ionization (SESI) |SUPER SESI |Fossil Ion Technology, Spain |https://www.fossiliontech.com/ | |- |Soft Ionization by Chemical Reaction In Transfer (SICRIT) |SICRIT |Plasmion GmbH, Germany |https://plasmion.com/ | |}
==References== {{Reflist}} {{Mass spectrometry}}
Category:Mass spectrometry Category:Ion source