electron-capture dissociation

Electron-capture dissociation was developed by Roman Zubarev and Neil Kelleher while in Fred McLafferty's lab at Cornell University. Irradiation of melittin 4+ ions and ubiquitin 10+ ions (trapped in FT-MS cell) by laser pulses not only resulted in peculiar c', z fragmentation but also charge reduction. It was suggested that if FT cell is modified to trap cations and electrons simultaneously, secondary electrons emitted by UV photons increases the charge reduction effect and c′, z• fragmentation. Replacing UV laser with EI source led to the development of this new technique.{{Cite journal|title=Towards An Understanding of the Mechanism of Electron-Capture Dissociation: A Historical Perspective and Modern Ideas|journal=European Journal of Mass Spectrometry|volume=8|issue=5|last1=Zubarev|first1=Roman|last2=Haselmann|year=2002|pages=337–349|doi=10.1255/ejms.517|s2cid=56411732 }}

Electron-capture dissociation typically involves a multiply protonated molecule M interacting with a free electron to form an odd-electron ion. Liberation of the electric potential energy results in fragmentation of the product ion.

:$[\backslash ce\{M\}\; +\; n\backslash ce\{H\}]^\{n+\}\; +\; \backslash ce\{e^-\; ->\}\; \backslash bigg[\; [\backslash ce\{M\}\; +\; n\backslash ce\{H\}]^\{(n-1)+\}\; \backslash bigg]^*\; \backslash ce\{->\; fragments\}$.

Rate of electron capture dissociation not only depends on the frequency of ion–electron fragmentation reactions but also on the number of ions in an ion–electron interaction volume. Electron current density and cross-section of ECD is directly proportional to fragmentation frequency.{{Cite journal|last1=Tsybin|first1=Youri O.|last2=Ramström|first2=Margareta|last3=Witt|first3=Matthias|last4=Baykut|first4=Gökhan|last5=Håkansson|first5=Per|date=2004-07-01|title=Peptide and protein characterization by high-rate electron capture dissociation Fourier transform ion cyclotron resonance mass spectrometry|journal=Journal of Mass Spectrometry|language=en|volume=39|issue=7|pages=719–729|doi=10.1002/jms.658|pmid=15282750|issn=1096-9888|bibcode=2004JMSp...39..719T|doi-access=free}}{{Cite journal|last1=Zubarev|first1=R. A.|last2=Horn|first2=D. M.|last3=Fridriksson|first3=E. K.|last4=Kelleher|first4=N. L.|last5=Kruger|first5=N. A.|last6=Lewis|first6=M. A.|last7=Carpenter|first7=B. K.|last8=McLafferty|first8=F. W.|date=2000-02-01|title=Electron capture dissociation for structural characterization of multiply charged protein cations|journal=Analytical Chemistry|volume=72|issue=3|pages=563–573|issn=0003-2700|pmid=10695143|doi=10.1021/ac990811p}} An indirectly heated dispenser cathode used as an electron source results in larger electron current and larger emitting surface area.{{Cite journal|last1=Haselmann|first1=Kim F.|last2=Budnik|first2=Bogdan A.|last3=Olsen|first3=Jesper V.|last4=Nielsen|first4=Michael L.|last5=Reis|first5=Celso A.|last6=Clausen|first6=Henrik|last7=Johnsen|first7=Anders H.|last8=Zubarev|first8=Roman A.|date=2001-07-01|title=Advantages of External Accumulation for Electron Capture Dissociation in Fourier Transform Mass Spectrometry|journal=Analytical Chemistry|volume=73|issue=13|pages=2998–3005|doi=10.1021/ac0015523|pmid=11467546|issn=0003-2700}}{{Cite journal|last1=Tsybin|first1=Youri O.|last2=Håkansson|first2=Per|last3=Budnik|first3=Bogdan A.|last4=Haselmann|first4=Kim F.|last5=Kjeldsen|first5=Frank|last6=Gorshkov|first6=Michael|last7=Zubarev|first7=Roman A.|date=2001-10-15|title=Improved low-energy electron injection systems for high rate electron capture dissociation in Fourier transform ion cyclotron resonance mass spectrometry|journal=Rapid Communications in Mass Spectrometry|language=en|volume=15|issue=19|pages=1849–1854|doi=10.1002/rcm.448|pmid=11565103|issn=1097-0231|bibcode=2001RCMS...15.1849T}}

:$\backslash text\{Efficiency\; of\; ECD\; MS/MS\}\; =\; \backslash frac\{\backslash text\{Total\; number(abundance)\; of\; fragment\; ions\}\}\{\backslash text\{Total\; number\; (abundance)\; of\; precursor\; ions\}\}$

ECD devices can be of two forms. It can trap analyte ions during the ECD stage or can undergo flow through mode where dissociation takes place as analyte ions flows continuously through the ECD region. Flow through mode has advantage over other mode because nearly all the analyte ion beam is used. However, that decreases the efficiency of ECD for flow through mode.{{Cite journal|last1=Baba|first1=Takashi|last2=Campbell|first2=J. Larry|last3=Le Blanc|first3=J. C. Yves|last4=Hager|first4=James W.|last5=Thomson|first5=Bruce A.|date=2015-01-06|title=Electron Capture Dissociation in a Branched Radio-Frequency Ion Trap|journal=Analytical Chemistry|volume=87|issue=1|pages=785–792|doi=10.1021/ac503773y|pmid=25423608|issn=0003-2700}}

ECD produces significantly different types of fragment ions (although primarily c- and z-type, b-ions have been identified in ECDLiu, H. & Håkansson, K. J Am Soc Mass Spectrom (2007) 18: 2007. doi:10.1016/j.jasms.2007.08.015; Haselmann and Schmidt, RCM 21:1003-1008, 2007; Cooper JASMS 16:1932-1940, 2005.) than other MS/MS fragmentation methods such as electron-detachment dissociation (EDD) (primarily a and x types),{{Cite journal|last1=Leach|first1=Franklin E.|last2=Wolff|first2=Jeremy J.|last3=Laremore|first3=Tatiana N.|last4=Linhardt|first4=Robert J.|last5=Amster|first5=I. Jonathan|title=Evaluation of the experimental parameters which control electron detachment dissociation, and their effect on the fragmentation efficiency of glycosaminoglycan carbohydrates|journal=International Journal of Mass Spectrometry|volume=276|issue=2–3|pages=110–115|doi=10.1016/j.ijms.2008.05.017|pmid=19802340|year=2008|pmc=2633944|bibcode=2008IJMSp.276..110L}}{{cite journal|author1=McFarland M. A.|author2=Marshall A. G.|author3=Hendrickson C. L.|author4=Nilsson C. L.|author5=Fredman P. |author-link5=Pam Fredman |author6=Månsson J. E.|date=May 2005|title=Structural characterization of the GM1 ganglioside by infrared multiphoton dissociation, electron capture dissociation, and electron detachment dissociation electrospray ionization FT-ICR MS/MS|journal=J. Am. Soc. Mass Spectrom.|volume=16|issue=5|pages=752–62|doi=10.1016/j.jasms.2005.02.001|pmid=15862776|doi-access=}}{{cite journal|author1=Wolff J. J.|author2=Laremore T. N.|author3=Busch A. M.|author4=Linhardt R. J.|author5=Amster I. J.|date=June 2008|title=Influence of charge state and sodium cationization on the electron detachment dissociation and infrared multiphoton dissociation of glycosaminoglycan oligosaccharides|journal=J. Am. Soc. Mass Spectrom.|volume=19|issue=6|pages=790–8|doi=10.1016/j.jasms.2008.03.010|pmc=2467392|pmid=18499037}} collision-induced dissociation (CID) (primarily b{{cite journal|author=Harrison A. G.|year=2009|title=To b or not to b: the ongoing saga of peptide b ions|journal=Mass Spectrom. Rev.|volume=28|issue=4|pages=640–54|bibcode=2009MSRv...28..640H|doi=10.1002/mas.20228|pmid=19338048}} and y type) and infrared multiphoton dissociation. CID and IRMPD introduce internal vibrational energy in some way or another, causing loss of post-translational modifications during fragmentation. In ECD, unique fragments (and complementary to CID) are observed,{{Cite journal|last1=Creese|first1=Andrew J.|last2=Cooper|first2=Helen J.|date=2007-05-01|title=Liquid chromatography electron capture dissociation tandem mass spectrometry (LC-ECD-MS/MS) versus liquid chromatography collision-induced dissociation tandem mass spectrometry (LC-CID-MS/MS) for the identification of proteins|journal=Journal of the American Society for Mass Spectrometry|language=en|volume=18|issue=5|pages=891–897|doi=10.1016/j.jasms.2007.01.008|pmid=17350280|pmc=2572008|issn=1044-0305}} and the ability to fragment whole macromolecules effectively has been promising.

Although ECD is primarily used in Fourier transform ion cyclotron resonance mass spectrometry,{{cite journal|author1=Cooper H. J.|author2=Håkansson K.|author3=Marshall A. G.|year=2005|title=The role of electron capture dissociation in biomolecular analysis|journal=Mass Spectrometry Reviews|volume=24|issue=2|pages=201–22|bibcode=2005MSRv...24..201C|doi=10.1002/mas.20014|pmid=15389856}} investigators have indicated that it has been successfully used in an ion-trap mass spectrometer.Baba et al., Anal. Chem., 76:4263–4266, 2004.{{Cite journal|last1=Ding|first1=Li|last2=Brancia|first2=Francesco L.|date=2006-03-01|title=Electron Capture Dissociation in a Digital Ion Trap Mass Spectrometer|journal=Analytical Chemistry|volume=78|issue=6|pages=1995–2000|doi=10.1021/ac0519007|pmid=16536438|issn=0003-2700}}{{Cite journal|last1=Deguchi|first1=Kisaburo|last2=Ito|first2=Hiroki|last3=Baba|first3=Takashi|last4=Hirabayashi|first4=Atsumu|last5=Nakagawa|first5=Hiroaki|last6=Fumoto|first6=Masataka|last7=Hinou|first7=Hiroshi|last8=Nishimura|first8=Shin-Ichiro|date=2007-03-15|title=Structural analysis of O-glycopeptides employing negative- and positive-ion multi-stage mass spectra obtained by collision-induced and electron-capture dissociations in linear ion trap time-of-flight mass spectrometry|journal=Rapid Communications in Mass Spectrometry|language=en|volume=21|issue=5|pages=691–698|doi=10.1002/rcm.2885|pmid=17279605|issn=1097-0231|bibcode=2007RCMS...21..691D}} ECD can also do rapid integration of multiple scans in FTICR-MS if put in a combination with external accumulation.

ECD is a recently introduced MS/MS fragmentation technique and is still being investigated.{{cite journal|author1=Syrstad E. A.|author2=Turecek F.|year=2005|title=Toward a general mechanism of electron capture dissociation|journal=J. Am. Soc. Mass Spectrom.|volume=16|issue=2|pages=208–24|doi=10.1016/j.jasms.2004.11.001|pmid=15694771|s2cid=756042 |doi-access=}}{{cite journal|author1=Savitski M. M.|author2=Kjeldsen F.|author3=Nielsen M. L.|author4=Zubarev R. A.|year=2006|title=Complementary sequence preferences of electron-capture dissociation and vibrational excitation in fragmentation of polypeptide polycations|journal=Angew. Chem. Int. Ed. Engl.|volume=45|issue=32|pages=5301–3|doi=10.1002/anie.200601240|pmid=16847865}} The mechanism of ECD is still under debate but appears not to necessarily break the weakest bond and is therefore thought to be a fast process (nonergodic) where energy is not free to relax intramolecularly. Suggestions have been made that radical reactions initiated by the electron may be responsible for the action of ECD.{{cite journal|author1=Leymarie N.|author2=Costello C. E.|author3=OConnor P. B.|year=2003|title=Electron Capture Dissociation Initiates a Free Radical Reaction Cascade|journal=J. Am. Chem. Soc.|volume=125|issue=29|pages=8949–8958|doi=10.1021/ja028831n|pmid=12862492}} In a similar MS/MS fragmentation technique called electron-transfer dissociation, the electrons are transferred by collision between the analyte cations and reagent anions.{{Cite journal|last1=Coon|first1=Joshua J.|last2=Shabanowitz|first2=Jeffrey|last3=Hunt|first3=Donald F.|last4=Syka|first4=John E. P.|date=2005-06-01|title=Electron transfer dissociation of peptide anions|journal=Journal of the American Society for Mass Spectrometry|language=en|volume=16|issue=6|pages=880–882|doi=10.1016/j.jasms.2005.01.015|pmid=15907703|issn=1044-0305|doi-access=}}{{cite journal|vauthors=Zubarev RA, Zubarev AR, Savitski MM|year=2008|title=Electron capture/transfer versus collisionally activated/induced dissociations: solo or duet?|journal=J. Am. Soc. Mass Spectrom.|volume=19|issue=6|pages=753–61|doi=10.1016/j.jasms.2008.03.007|pmid=18499036|doi-access=}}{{cite journal|last1=Hamidane|first1=Hisham Ben|last2=Chiappe|first2=Diego|last3=Hartmer|first3=Ralf|last4=Vorobyev|first4=Aleksey|last5=Moniatte|first5=Marc|last6=Tsybin|first6=Yury O.|year=2009|title=Electron capture and transfer dissociation: Peptide structure analysis at different ion internal energy levels|journal=Journal of the American Society for Mass Spectrometry|volume=20|issue=4|pages=567–575|doi=10.1016/j.jasms.2008.11.016|pmid=19112028|issn=1044-0305|doi-access=free}}

ECD itself and combined with other MS is very useful for proteins and peptides containing multiple disulfide bonds. FTICR combined with ECD helps to recognize peptides containing disulfide bonds. ECD could also access important sequence information by activation of higher charged proteins. Moreover, disulfide bond cleavage takes place by ECD of multiply charge proteins or peptides produced by ESI.{{Cite journal|last1=Zubarev|first1=Roman A.|last2=Kruger|first2=Nathan A.|last3=Fridriksson|first3=Einar K.|last4=Lewis|first4=Mark A.|last5=Horn|first5=David M.|last6=Carpenter|first6=Barry K.|last7=McLafferty|first7=Fred W.|date=1999-03-01|title=Electron Capture Dissociation of Gaseous Multiply-Charged Proteins Is Favored at Disulfide Bonds and Other Sites of High Hydrogen Atom Affinity|journal=Journal of the American Chemical Society|volume=121|issue=12|pages=2857–2862|doi=10.1021/ja981948k|issn=0002-7863}} Electron capture by these proteins releases H atom, captured by the disulfide bond to cause its dissociation.{{Cite book|title=Principles and practice of biological mass spectrometry|last=Dass|first=Chhabil|year=2001|isbn=978-0471330530|location=New York}}

:RS-SR' + \bullet H -> R-S(H) \bullet S-R' -> RSH{} + \bullet SR'

ECD with UV-based activation increases the top-down MS sequence coverage of disulfide bond containing proteins and cleaves a disulfide bond homolytically to produce two separated thiol radicals. This technique was observed with insulin and ribonuclease, which led them to cleave up to three disulfide bonds and increase the sequence coverage.{{Cite journal|last1=Wongkongkathep|first1=Piriya|last2=Li|first2=Huilin|last3=Zhang|first3=Xing|last4=Loo|first4=Rachel R. Ogorzalek|last5=Julian|first5=Ryan R.|last6=Loo|first6=Joseph A.|title=Enhancing protein disulfide bond cleavage by UV excitation and electron capture dissociation for top-down mass spectrometry|journal=International Journal of Mass Spectrometry|volume=390|pages=137–145|doi=10.1016/j.ijms.2015.07.008|pmid=26644781|pmc=4669582|year=2015|bibcode=2015IJMSp.390..137W}}

ECD-MS fragments can retain posttranslational modifications such as carboxylation, phosphorylation{{Cite journal|last1=Creese|first1=Andrew J.|last2=Cooper|first2=Helen J.|date=2008-09-01|title=The effect of phosphorylation on the electron capture dissociation of peptide ions|journal=Journal of the American Society for Mass Spectrometry|language=en|volume=19|issue=9|pages=1263–1274|doi=10.1016/j.jasms.2008.05.015|pmid=18585055|pmc=2570175|issn=1044-0305}}{{Cite journal|last1=Woodling|first1=Kellie A.|last2=Eyler|first2=John R.|last3=Tsybin|first3=Yury O.|last4=Nilsson|first4=Carol L.|last5=Marshall|first5=Alan G.|last6=Edison|first6=Arthur S.|last7=Al-Naggar|first7=Iman M.|last8=Bubb|first8=Michael R.|date=2007-12-01|title=Identification of single and double sites of phosphorylation by ECD FT-ICR/MS in peptides related to the phosphorylation site domain of the myristoylated alanine-rich c kinase protein|journal=Journal of the American Society for Mass Spectrometry|language=en|volume=18|issue=12|pages=2137–2145|doi=10.1016/j.jasms.2007.09.010|pmid=17962038|issn=1044-0305|doi-access=free}} and O-glycosylation.{{Cite journal|last1=Mirgorodskaya|first1=E.|last2=Roepstorff|first2=P.|last3=Zubarev|first3=R. A.|date=1999-10-01|title=Localization of O-Glycosylation Sites in Peptides by Electron Capture Dissociation in a Fourier Transform Mass Spectrometer|journal=Analytical Chemistry|volume=71|issue=20|pages=4431–4436|doi=10.1021/ac990578v|pmid=10546526|issn=0003-2700}}{{Cite journal|last1=Renfrow|first1=Matthew B.|last2=Cooper|first2=Helen J.|last3=Tomana|first3=Milan|last4=Kulhavy|first4=Rose|last5=Hiki|first5=Yoshiyuki|last6=Toma|first6=Kazunori|last7=Emmett|first7=Mark R.|last8=Mestecky|first8=Jiri|last9=Marshall|first9=Alan G.|date=2005-05-13|title=Determination of Aberrant O-Glycosylation in the IgA1 Hinge Region by Electron Capture Dissociation Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry|journal=Journal of Biological Chemistry|language=en|volume=280|issue=19|pages=19136–19145|doi=10.1074/jbc.m411368200|issn=0021-9258|pmid=15728186|doi-access=free}} ECD has the potential to do the top-down characterization of the major types of posttranslational modifications in proteins. It successfully cleaved 87 of 208 backbone bonds and provided the first direct characterization of a phosphoprotein, bovine β casein, simultaneously restricting the location of five phosphorylation sites. It has advantages over CAD to measure the degree of phosphorylation with a minimum number of losses of phosphates and for phosphopeptide/phosphoprotein mapping, which makes ECD a superior technique.{{Cite journal|last1=Shi|first1=Stone D.-H.|last2=Hemling|first2=Mark E.|last3=Carr|first3=Steven A.|last4=Horn|first4=David M.|last5=Lindh|first5=Ingemar|last6=McLafferty|first6=Fred W.|date=2001-01-01|title=Phosphopeptide/Phosphoprotein Mapping by Electron Capture Dissociation Mass Spectrometry|journal=Analytical Chemistry|volume=73|issue=1|pages=19–22|doi=10.1021/ac000703z|pmid=11195502|issn=0003-2700}}

File:Schematic of AP-ECD source.png

ECD has been coupled with capillary electrophoresis (CE) to gain insight into structural analysis of mixture of peptides and protein digest.{{Cite journal|last=Tsybin, Håkansson, Wetterhall, Markides, Bergquist|title=Capillary Electrophoresis and Electron Capture Dissociation Fourier Transform Ion Cyclotron Resonance Mass Spectrometry for Peptide Mixture and Protein Digest Analysis|journal=European Journal of Mass Spectrometry|volume=8|issue=5|pages=389–395|doi=10.1255/ejms.514|year=2017|s2cid=98604321 }} Micro-HPLC combined with ECD FTICR was used to analyze pepsin digest of cytochrome c.{{Cite journal|last1=Davidson|first1=Walter|last2=Frego|first2=Lee|date=2002-05-30|title=Micro-high-performance liquid chromatography/Fourier transform mass spectrometry with electron-capture dissociation for the analysis of protein enzymatic digests|journal=Rapid Communications in Mass Spectrometry|language=en|volume=16|issue=10|pages=993–998|doi=10.1002/rcm.666|pmid=11968133|issn=1097-0231|bibcode=2002RCMS...16..993D}} Sequence tags were provided by analysis of a mixture of peptides and tryptic digest of bovine serum albumin when LC ECD FTICR MS was used.{{Cite journal|last1=Palmblad|first1=Magnus|last2=Tsybin|first2=Youri O.|last3=Ramström|first3=Margareta|last4=Bergquist|first4=Jonas|last5=Håkansson|first5=Per|date=2002-05-30|title=Liquid chromatography and electron-capture dissociation in Fourier transform ion cyclotron resonance mass spectrometry|journal=Rapid Communications in Mass Spectrometry|language=en|volume=16|issue=10|pages=988–992|doi=10.1002/rcm.667|pmid=11968132|issn=1097-0231|bibcode=2002RCMS...16..988P}} Additionally, LC-ECD-MS/MS is provides longer sequence tags than LC-CID-MS/MS for identification of proteins. ECD devices using radio frequency quadrupole ion trap are relevant for high-throughput proteomics.{{Cite journal|last1=Satake|first1=Hiroyuki|last2=Hasegawa|first2=Hideki|last3=Hirabayashi|first3=Atsumu|last4=Hashimoto|first4=Yuichiro|last5=Baba|first5=Takashi|last6=Masuda|first6=Katsuyoshi|date=2007-11-01|title=Fast Multiple Electron Capture Dissociation in a Linear Radio Frequency Quadrupole Ion Trap|journal=Analytical Chemistry|volume=79|issue=22|pages=8755–8761|doi=10.1021/ac071462z|pmid=17902701|issn=0003-2700}} Recently, Atmospheric pressure electron capture dissociation (AP-ECD) is emerging as a better technique because it can be implemented as a stand-alone ion-source device and doesn't require any modification of the main instrument.{{Cite journal|last1=Robb|first1=Damon B.|last2=Rogalski|first2=Jason C.|last3=Kast|first3=Juergen|last4=Blades|first4=Michael W.|date=2011-10-01|title=A New Ion Source and Procedures for Atmospheric Pressure-Electron Capture Dissociation of Peptides|journal=Journal of the American Society for Mass Spectrometry|language=en|volume=22|issue=10|pages=1699–706|doi=10.1007/s13361-011-0202-0|pmid=21952883|issn=1044-0305|bibcode=2011JASMS..22.1699R|s2cid=6700021 |doi-access=}}{{Cite journal|last1=Robb|first1=Damon B.|last2=Rogalski|first2=Jason C.|last3=Kast|first3=Juergen|last4=Blades|first4=Michael W.|date=2012-05-01|title=Liquid Chromatography–Atmospheric Pressure Electron Capture Dissociation Mass Spectrometry for the Structural Analysis of Peptides and Proteins|journal=Analytical Chemistry|volume=84|issue=9|pages=4221–4226|doi=10.1021/ac300648g|pmid=22494041|issn=0003-2700}}

Analysis of proteins can be done by either using top-down or bottom-up approach. However, better sequence coverage is provided by top-down analysis.{{Cite journal|last1=Kelleher|first1=Neil L.|last2=Lin|first2=Hong Y.|last3=Valaskovic|first3=Gary A.|last4=Aaserud|first4=David J.|last5=Fridriksson|first5=Einar K.|last6=McLafferty|first6=Fred W.|date=1999-02-01|title=Top Down versus Bottom Up Protein Characterization by Tandem High-Resolution Mass Spectrometry|journal=Journal of the American Chemical Society|volume=121|issue=4|pages=806–812|doi=10.1021/ja973655h|issn=0002-7863}} Combination of ECD with FTICR MS has resulted in popularity of this approach. It has also helped in determining the multiple modification sites in intact proteins.{{Cite journal|last1=Chalmers|first1=Michael J.|last2=Håkansson|first2=Kristina|last3=Johnson|first3=Robert|last4=Smith|first4=Richard|last5=Shen|first5=Jianwei|last6=Emmett|first6=Mark R.|last7=Marshall|first7=Alan G.|date=2004-04-01|title=Protein kinase A phosphorylation characterized by tandem Fourier transform ion cyclotron resonance mass spectrometry|journal=Proteomics|language=en|volume=4|issue=4|pages=970–981|doi=10.1002/pmic.200300650|pmid=15048979|s2cid=21400646 |issn=1615-9861}}{{Cite journal|last1=Ge|first1=Ying|last2=Lawhorn|first2=Brian G.|last3=ElNaggar|first3=Mariam|last4=Strauss|first4=Erick|last5=Park|first5=Joo-Heon|last6=Begley|first6=Tadhg P.|last7=McLafferty|first7=Fred W.|date=2002-01-01|title=Top Down Characterization of Larger Proteins (45 kDa) by Electron Capture Dissociation Mass Spectrometry|journal=Journal of the American Chemical Society|volume=124|issue=4|pages=672–678|doi=10.1021/ja011335z|pmid=11804498|issn=0002-7863}} Native electron capture dissociation (NECD) was used to study cytochrome c dimer{{Cite journal|last1=Breuker|first1=Kathrin|last2=McLafferty|first2=Fred W.|date=2003-10-20|title=Native Electron Capture Dissociation for the Structural Characterization of Noncovalent Interactions in Native Cytochromec|journal=Angewandte Chemie International Edition|language=en|volume=42|issue=40|pages=4900–4904|doi=10.1002/anie.200351705|pmid=14579433|issn=1521-3773}} and has been recently used to elucidate iron-binding channels in horse spleen ferritin.{{Cite journal|last1=Skinner|first1=Owen S.|last2=McAnally|first2=Michael O.|last3=Van Duyne|first3=Richard P.|last4=Schatz|first4=George C.|last5=Breuker|first5=Kathrin|last6=Compton|first6=Philip D.|last7=Kelleher|first7=Neil L.|date=2017-10-17|title=Native Electron Capture Dissociation Maps to Iron-Binding Channels in Horse Spleen Ferritin|journal=Analytical Chemistry|volume=89|issue=20|pages=10711–10716|doi=10.1021/acs.analchem.7b01581|pmid=28938074|pmc=5647560|issn=0003-2700}}

ECD studies of polyalkene glycols, polyamides, polyacrylates and polyesters are useful for understanding composition of polymer samples. It has become a powerful technique to analyze structural information about precursor ions during MS/MS for synthetic polymers. ECD's single bond cleavage tendency makes the interpretation of product ion scans simple and easy for polymer chemistry.{{Cite journal|last=Hart-Smith|first=Gene|title=A review of electron-capture and electron-transfer dissociation tandem mass spectrometry in polymer chemistry|journal=Analytica Chimica Acta|volume=808|pages=44–55|doi=10.1016/j.aca.2013.09.033|pmid=24370092|year=2014}}

• Electron capture ionization
• Electron–capture mass spectrometry
• RRKM theory

{{Reflist}}

{{Mass spectrometry}}

Category:Tandem mass spectrometry