Difference between revisions of "Resolution (mass spectrometry)"
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−  }}  +  def=In a [[mass spectrum]], the observed [[m/z]] value divided by the smallest difference Δ(m/z) for two ions that can be separated: (m/z)/Δ(m/z). 
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+  :Note 1: The m/z value at which the measurement was made should be reported.  
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+  :Note 2: The definition and method of measurement of Δ(m/z) should be reported. Commonly this is performed using peak width measured at a specified percentage of peak height.  
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+  :Note 3: Alternatively Δ(m/z) is defined as the separation between two adjacent equal magnitude peaks such that the valley between them is a specified fraction of the peak height, for example as measured by peak matching.  
+  rel=[[Resolving power]]  
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−  +  G. L. Glish, D. J. Burinsky. J. Am. Soc. Mass Spectrom. 19, 161 (2008).  
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−  +  J. Laskin, J. H. Futrell. Mass Spectrom. Rev. 24, 135 (2005).  
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[http://goldbook.iupac.org/R05318.html resolution in mass spectroscopy] <nowiki>[</nowiki>sic<nowiki>]</nowiki>  [http://goldbook.iupac.org/R05318.html resolution in mass spectroscopy] <nowiki>[</nowiki>sic<nowiki>]</nowiki>  
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(10 per cent valley definition): Let two peaks of equal height in a mass spectrum at masses ''m'' and ''m  Δm'' be separated by a valley which at its lowest point is just 10 per cent of the height of either peak. For similar peaks at a mass exceeding m, let the height of the valley at its lowest point be more (by any amount) than ten per cent of either peak height. Then the resolution (10 per cent valley definition) is ''m/Δm''. It is usually a function of ''m''. The ratio ''m/Δm'' should be given for a number of values of .  (10 per cent valley definition): Let two peaks of equal height in a mass spectrum at masses ''m'' and ''m  Δm'' be separated by a valley which at its lowest point is just 10 per cent of the height of either peak. For similar peaks at a mass exceeding m, let the height of the valley at its lowest point be more (by any amount) than ten per cent of either peak height. Then the resolution (10 per cent valley definition) is ''m/Δm''. It is usually a function of ''m''. The ratio ''m/Δm'' should be given for a number of values of .  
−  (peak width definition): For a single peak made up of singly charged ions at mass in a mass spectrum, the resolution may be expressed as  +  (peak width definition): For a single peak made up of singly charged ions at mass in a mass spectrum, the resolution may be expressed as ''m/Δm'' where Δm is the width of the peak at a height which is a specified fraction of the maximum peak height. It is recommended that one of three values 50%, 5% or 0.5% should always be used. For an isolated symmetrical peak recorded with a system which is linear in the range between 5% and 10% levels of the peak, the 5% peak width definition is technically equivalent to the 10% valley definition. A common standard is the definition of resolution based upon being Full Width of the peak at Half its Maximum height, sometimes abbreviated 'FWHM'. This acronym should preferably be defined the first time it is used. 
Source: PAC, 1991, 63, 1541 ([[Recommendations for nomenclature and symbolism for mass spectroscopy]] (including an appendix of terms used in vacuum technology). (Recommendations 1991)) on page 1554  Source: PAC, 1991, 63, 1541 ([[Recommendations for nomenclature and symbolism for mass spectroscopy]] (including an appendix of terms used in vacuum technology). (Recommendations 1991)) on page 1554  
[[Orange Book]], p. 203  [[Orange Book]], p. 203  
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[[Resolution: 10 Per Cent Valley Definition]]  [[Resolution: 10 Per Cent Valley Definition]]  
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For a single peak made up of singly charged ions at mass m in a [[Mass Spectrummass spectrum]], the resolution may be expressed as m / Δm, where Δm is the width of the peak at a height which is a specified fraction of the maximum peak height. It is recommended that one of three values 50%, 5% or 0.5% should always be used. (Note that for an isolated symmetrical peak recorded with a system which is linear in the range between 5% and 10% levels of the peak, the 5% peak width definition is equivalent to the 10% valley definition. A common standard is the definition of resolution based upon Δm being Full Width of the peak at Half its Maximum (FWHM) height.  For a single peak made up of singly charged ions at mass m in a [[Mass Spectrummass spectrum]], the resolution may be expressed as m / Δm, where Δm is the width of the peak at a height which is a specified fraction of the maximum peak height. It is recommended that one of three values 50%, 5% or 0.5% should always be used. (Note that for an isolated symmetrical peak recorded with a system which is linear in the range between 5% and 10% levels of the peak, the 5% peak width definition is equivalent to the 10% valley definition. A common standard is the definition of resolution based upon Δm being Full Width of the peak at Half its Maximum (FWHM) height.  
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−  *  +  ==External links== 
+  *Urban, J., Afseth, N.K., Štys, D.: Fundamental definitions and confusions in mass spectrometry about mass assignment, centroiding and resolution. TrAC Trends in Analytical Chemistry. 53, 126136 (2014); {{doi}}10.1016/j.trac.2013.07.010  
[[Category:Resolution]]  [[Category:Resolution]] 
Latest revision as of 22:29, 16 May 2022
IUPAC RECOMMENDATIONS 2013 
Resolution (mass spectrometry) 

In a mass spectrum, the observed m/z value divided by the smallest difference Δ(m/z) for two ions that can be separated: (m/z)/Δ(m/z).

Related Term(s): Resolving power 
Reference(s):
IUPAC. Analytical Division. Compendium of Analytical Nomenclature (the Orange Book). Definitive Rules, 1979. Compiled by J. Inczédy, T. Lengyel, A. M. Ure. Blackwell Scientific Publications, Oxford (1997). Online corrected version: http://www.iupac.org /publications/analytical compendium (2000). IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML online corrected version: http://goldbook.iupac.org (2006) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. G. L. Glish, D. J. Burinsky. J. Am. Soc. Mass Spectrom. 19, 161 (2008). J. Laskin, J. H. Futrell. Mass Spectrom. Rev. 24, 135 (2005). 
From Definitions of Terms Relating to Mass Spectrometry (IUPAC Recommendations 2013); DOI: 10.1351/PACREC060406 © IUPAC 2013. 
Gold Book
GOLD BOOK DEFINITION
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). 
Resolution (mass spectrometry) 

resolution in mass spectroscopy [sic] (energy): By analogy with the peak width definition for mass resolution, a peak showing the number of ions as a function of their translational energy should be used to give a value for the energy resolution. (10 per cent valley definition): Let two peaks of equal height in a mass spectrum at masses m and m  Δm be separated by a valley which at its lowest point is just 10 per cent of the height of either peak. For similar peaks at a mass exceeding m, let the height of the valley at its lowest point be more (by any amount) than ten per cent of either peak height. Then the resolution (10 per cent valley definition) is m/Δm. It is usually a function of m. The ratio m/Δm should be given for a number of values of . (peak width definition): For a single peak made up of singly charged ions at mass in a mass spectrum, the resolution may be expressed as m/Δm where Δm is the width of the peak at a height which is a specified fraction of the maximum peak height. It is recommended that one of three values 50%, 5% or 0.5% should always be used. For an isolated symmetrical peak recorded with a system which is linear in the range between 5% and 10% levels of the peak, the 5% peak width definition is technically equivalent to the 10% valley definition. A common standard is the definition of resolution based upon being Full Width of the peak at Half its Maximum height, sometimes abbreviated 'FWHM'. This acronym should preferably be defined the first time it is used. Source: PAC, 1991, 63, 1541 (Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)) on page 1554 Orange Book, p. 203 
IUPAC Gold Book 
Index of Gold Book Terms 
Orange Book
ORANGE BOOK DEFINITION
IUPAC. Analytical Division. Compendium of Analytical Nomenclature (the Orange Book). Definitive Rules, 1979. 
Resolution (mass spectrometry) 

Resolution: 10 Per Cent Valley Definition Let two peaks of equal height in a mass spectrum at masses m and m  Δm be separated by a valley which at its lowest point is just 10% of the height of either peak. For similar peaks at a mass exceeding m , let the height of the valley at its lowest point be more (by any amount) than 10% of either peak. Then the resolution (10% valley definition) is m / Δm. The ratio m /Δm should be given for a number of values of m. Resolution: Peak Width Definition For a single peak made up of singly charged ions at mass m in a mass spectrum, the resolution may be expressed as m / Δm, where Δm is the width of the peak at a height which is a specified fraction of the maximum peak height. It is recommended that one of three values 50%, 5% or 0.5% should always be used. (Note that for an isolated symmetrical peak recorded with a system which is linear in the range between 5% and 10% levels of the peak, the 5% peak width definition is equivalent to the 10% valley definition. A common standard is the definition of resolution based upon Δm being Full Width of the peak at Half its Maximum (FWHM) height. 
IUPAC 1997 Orange Book Chapter 12 
Index of Orange Book Terms 
Resolution and resolving power controversy
QUOTED TEXT FROM IUPAC RECOMMENDATIONS 2013 
The IUPAC definition of resolution in mass spectrometry expresses this value as m/Δm, where m is the mass of the ion of interest and Δm is the peak width (peak width definition) or the spacing between two equal intensity peaks with a valley between them no more than 10 % of their height (10 % valley definition) [1]. Resolving power in mass spectrometry is defined as the ability of an instrument or measurement procedure to distinguish between two peaks at m/z values differing by a small amount and expressed as the peak width in mass units [2]. Mass resolving power is defined separately as m/Δm in a manner similar to that given above for mass resolution [3]. These definitions of mass resolving power and resolving power in mass spectrometry are contradictory, the former is expressed as a dimensionless ratio and the latter as a mass. The definitions for resolution in mass spectrometry and resolving power in mass spectrometry come from Todd's 1991 recommendations [4], and the definition for mass resolving power comes from Beynon's 1978 recommendations [5]. Beynon's work contains no definition for mass resolution.
Alternative definitions for resolution and resolving power in mass spectrometry have been proposed [6][7]. It has been suggested that resolution be given by Δm and resolving power by m/Δm; however, these definitions are not widely used. The majority of the mass spectrometry community uses resolution as defined by IUPAC. The term resolving power is not widely used as a synonym for resolution. In this document, the IUPAC definition of resolution in mass spectrometry remains in place. The definition of resolving power has been adapted from the current IUPAC definition of mass resolving power. 
From Definitions of Terms Relating to Mass Spectrometry (IUPAC Recommendations 2013); DOI: 10.1351/PACREC060406 © IUPAC 2013. 

Books defining resolution and/or resolving power
Books using resolution is m/Δm
 Mass Spectrometry and its Applications to Organic Chemistry
 J. H. Beynon, Elsevier, 1960
 p. 51 "The terms 'resolution' and 'resolving power' have been used a great deal in the above discussion. It has been assumed that the doublet is 'resolved' when its constituent ion species are 'separated' and that the difficult of separation or 'resolving power' necessary to separate the adjacent mass peaks is given by M/ΔM."
 Mass Spectrometry  Organic Chemical Applications
 Klaus Biemann, McGrawHill, 1962
 (p. 13) the term resolution is used in different ways  Throughout this book resolution will be considered as M/ΔM
 Lasers and Mass Spectrometry
 By David M. Lubman, Oxford University Press US, 1990, ISBN 0195059298
 Interpretation of Mass Spectra
 Fred W. McLafferty, Turecek, University Science Books, 1993, Language: English, ISBN 0935702253
 Mass Spectrometry: Clinical and Biomedical Applications
 By Dominic M. Desiderio, Springer, 1993, ISBN 0306442612
 Practical Organic Mass Spectrometry: A Guide for Chemical and Biochemical Analysis
 J. R. Chapman, Wiley_Default, 1995, ISBN 047195831X
 Mass Spectrometry for Chemists and Biochemists
 Robert Alexander Walker Johnstone, M. E. Rose, Cambridge University Press, 1996, ISBN 0521424976
 Introduction to Mass Spectrometry
 By J. Throck Watson, LippincottRaven, 1997, ISBN 0397516886
 Ionization Methods in Organic Mass Spectrometry
 By Alison E. Ashcroft, Royal Society of Chemistry (Great Britain), Royal Society of Chemistry, 1997, ISBN 0854045708
 Accelerator Mass Spectrometry: Ultrasensitive Analysis for Global Science
 Claudio Tuniz, John R. Bird, Gregory F. Herzog, David Fink, CRC Press, 1998, ISBN 0849345383
 Mass Spectrometry in Biology & Medicine
 By A. L. Burlingame, Steven A. Carr, Michael A. Baldwin, Humana Press, 1999, ISBN 0896037991
 Mass Spectrometry and Genomic Analysis
 J. Nicholas Housby, Springer, 2001, ISBN 0792371739
 Mass Spectrometry Basics
 Christopher G. Herbert, Robert Alexander Walker Johnstone, CRC Press, 2002, ISBN 0849313546
 Liquid Chromatography Mass Spectrometry: An Introduction Robert E. Ardrey
 Wiley, 2003, ISBN 0471498017
 Mass Spectrometry: A Textbook
 Jurgen H. Gross, Springer, 2004, ISBN 3540407391
 Quadrupole Ion Trap Mass Spectrometry
 By Raymond E. March, John F. Todd, WileyIEEE, 2005, ISBN 0471717975
 The Expanding Role of Mass Spectrometry in Biotechnology
 Gary Siuzdak, McC Pr, 2006, ISBN 0974245127
 Quantitative Applications of Mass Spectrometry
 Pietro Traldi, Franco Magno, Irma Lavagnini, Roberta Seraglia, Wiley, 2006, ISBN 0470025166
 Assigning Structures to Ions in Mass Spectrometry
 John L. Holmes, Christiane Aubry, Paul M. Mayer, CRC, 2006, ISBN 0849319501
 Mass Spectrometry: Principles and Applications
 Edmond de Hoffmann, Vincent Stroobant, WileyInterscience, 2007
 ISBN 047003310X
 Mass Spectrometry: Principles and Applications
 Edmond de Hoffmann, Jean Charette, Vincent Stroobant, Wiley, 1996, ISBN 0471966975
 p 287: "Resolution: the ratio of m/δm where m and m+δm are the mass numbers of the two ions that yield neighboring peaks with a valley depth of x% of the weakest peak's intensity."
 Quantitative Proteomics by Mass Spectrometry (Methods in Molecular Biology)
 Salvatore Sechi, Humana Press, 2007, ISBN 1588295710
 Computational Methods for Mass Spectrometry Proteomics
 Ingvar Eidhammer, Kristian Flikka, Lennart Martens, SveinOle Mikalsen, WileyInterscience, 2008, ISBN 0470512970
Books that use resolution is Δm
 Mass Spectrometry Desk Reference
 David Sparkman, Global View, 2006, ISBN 0966081390
 "Incorrect: resolution  when defined in the same way as resolving power. Resolution is the inverse of resolving power and expressed as ΔM at M."
 Introduction to Mass Spectrometry: Instrumentation, Applications, and Strategies for Data Interpretation
 J. Throck Watson, O. David Sparkman, Wiley, 2007, Language: English, ISBN 0470516348
 Fundamentals of Contemporary Mass Spectrometry
 Chhabil Dass, 2007, ISBN 0471682292
 p. 68: "[mass resolution] is the inverse of resolving power (RP), given as RP=m/Δm"
 Proteomics in Practice: A Guide to Successful Experimental Design
 Reiner Westermeier, Tom Naven, HansRudolf H??pker, Wiley, 2008, ISBN 3527319417
Early manuscripts defining resolution and/or resolving power
 F. Aston, Bakerian lecture. "A new massspectrograph and the whole number rule", Proc. R. Soc. London, 1927. http://dx.doi.org/10.1098/rspa.1927.0106
 "Its resolving power was sufficient to separate mass lines differing by about 1 in 130 and its accuracy of measurement was about 1 in 1000. […] It was finally decided that the increase of resolution could best be obtained by doubling the angles of electric and magnetic deflection, and sharpening the lines by the use of finer slits placed further apart, in addition special methods were considered for the necessary increase of accuracy in measurement. After numerous setbacks all these objects have been successfully carried out. The new instrument has five times the resolving power of the old one, far more than sufficient to separate the mass lines of the heaviest element known. Its accuracy is 1 in 10,000 which is just sufficient to give rough first order values of the divergences from whole numbers."
 F.W. Aston, "Atoms and their Packing Fractions", Nature, 120 (1927) 956959. http://dx.doi.org/10.1038/120956a0
 "the resolution of the mass lines of the heavier elements […] resolving power was suflicient to separate mass lines differing by about 1 in 130, and its accuracy of measurement was about 1 in 1000. […] new instrument has five times the resolving power of the old one, far more than sufficient to separate the mass lines of the heaviest element known. Its accuracy is 1 in 10,000, […]"
 W. Bleakney, "A New Method of Positive Ray Analysis and Its Application to the Measurement of Ionization Potentials in Mercury Vapor," Phys. Rev., 34 (1929) 157160. http://dx.doi.org/10.1103/PhysRev.34.157
 "While the resolving power of the analyzer is not particularly high, yet it has proved to be excellent for the purposes for which it was designed."
 F.W. Aston, The Isotopic Constitution and Atomic Weight of Lead from Different Sources, Proceedings of the Royal Society of London Series aContaining Papers of a Mathematical and Physical Character, 140 (1933) 535543. http://dx.doi.org/10.1098/rspa.1933.0087
 "a view to increasing resolving power […] Increased accuracy has been obtained, but full advantage cannot be taken of it until higher resolution is available on account of the inevitable error involved in measuring the distance between lines not of the same intensity"
 A.J. Dempster, New Methods in Mass Spectroscopy, Proceedings of the American Philosophical Society, 75 (1935) 755767. http://dx.doi.org/
 "The main limitation to increased accuracy in mass determinations is in the comparatively small resolving power of the mass spectrographs hitherto used. On page 78 of "Mass Spectra and Isotopes," Aston says: "The resolving power is sufficient to separate lines differing by I in 6oo, . . . since the lines are irregularly curved and change in shape as one moves from one end of the spectrum to the other, it is impossible to assign positions to them relative to the fiducial spot with sufficient accuracy to approach the figure of 1 in 10,000 aimed at. This can only be done by measuring the distance between lines of approximately the same intensity and therefore the same shape, when they are quite […] The spectra reproduced by Bainbridge 1 show a resolving power of approximately 1 in 200, that is, the image produced by the atoms of one element is so broad that the value obtained for the weight, if one side of the image is observed, differs by 1 in 200 from the weight obtained if the other side is used. Of course, the center is measured but some of the mass determinations given by Dr. Bainbridge involve estimating the center of the image with an accuracy of one hundredth of the width of the image. While the progress made by Dr. Aston and Dr. Bainbridge has been most re markable, it is permissible to hope that an increase in sharpness of the images with a corresponding increase in resolving power would give a still greater precision in atomic mass determinations.close together. The accuracy of 1 in 1O,OOO estimated by Dr. Aston implies the judging of the centers, […] As explained in the introduction, this is primarily a problem of increased resolution with greater sharpness of the ion images. […] The resolving power with this comparatively wide slit is I in 1OOO."
Other IUPAC definitions of resolution
Gold Book
GOLD BOOK DEFINITION
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). 
Resolution (mass spectrometry) 

http://goldbook.iupac.org/R05319.html resolution (in optical spectroscopy) Wavenumber, wavelength or frequency difference of two still distinguishable lines in a spectrum. Source: Green Book, 2nd ed., p. 31

IUPAC Gold Book 
Index of Gold Book Terms 
Gold Book
GOLD BOOK DEFINITION
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). 
Resolution (mass spectrometry) 

http://goldbook.iupac.org/P04465.html
peak resolution, R_{s} (in chromatography) The separation of two peaks in terms of their average peak width at base (t R2 > t R1):
In the case of two adjacent peaks it may be assumed that w b1 ? w b2, and thus, the width of the second peak may be substituted for the average value:
Source: PAC, 1993, 65, 819 (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 847 Orange Book, p. 108 
IUPAC Gold Book 
Index of Gold Book Terms 
Gold Book
GOLD BOOK DEFINITION
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). 
Resolution (mass spectrometry) 

resolution (in gas chromatography) http://goldbook.iupac.org/R05317.html A characteristic of the separation of two adjacent peaks. It may be expressed according to the equation:
where R_{AB} is the resolution, d_{R} (A) and d_{R} (B) are the retention distances (time or volume) of each eluted component A and B, and w_{A} and w_{B} are the respective widths of each peak at its base. PAC, 1990, 62, 2167 (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2211 
IUPAC Gold Book 
Index of Gold Book Terms 
Gold Book
GOLD BOOK DEFINITION
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). 
Resolution (mass spectrometry) 

http://goldbook.iupac.org/E02113.html
energy resolution (in radiochemistry) A measurement, at given energy, of the smallest difference between the energies of two particles or photons capable of being distinguished by a radiation spectrometer. Source: PAC, 1994, 66, 2513 (Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)) on page 2519 
IUPAC Gold Book 
Index of Gold Book Terms 
Resolution and resolving power terminology in mass spectrometry
 ASMS 2022
 Poster MP 113
 Kermit K Murray
Premise
Nomenclature inconsistencies and conflicts can best be resolved through a detailed understanding of the origin and development of terms. The goal of this project is to investigate the origins and use as well as prior and current definitions of resolution and resolving power in order to make informed recommendations on the controversial and in some cases conflicting terminology.
Current definitions
In mass spectrometry, two peaks in a mass spectrum are resolved if they are distinguishable as separate. The degree to which the peaks are resolved can be quantified using the peak width or the separation between two peaks and is represented by Δ(m/z) where m/z is the masstocharge ratio. For singly charged ions, this can be expressed as Δm or, in older publications, as ΔM. The smallest value of Δm for which peaks are resolved is the limit of resolution. There are two general methods to determine Δm: peak width and valley:
Peak width: Δm is the peak width at a specified fraction of the peak height, for example at 50% Δm is the full width at half maximum
Valley: Δm is the separation between two equal height peaks that produces a valley a specified fraction of the height, for example 10%.
The 10% valley Δm is comparable to the 5% peak height Δm and approximately half that obtained from the FWHM. There are three general interpretations of the definitions of resolution and resolving power:
 the terms are equivalent and represented by m/Δm (Meyerson 1975, Murray 2013)
 resolution is m/Δm and resolving power is Δm (Price 1991, Todd 1991)
 resolving power is m/Δm and resolution is Δm (Beynon 1978).
Historical use
Prior to the Second World War, the term resolving power, defined as M/ΔM, was used almost exclusively. Resolution was used as a binary variable or as the limit of resolution. In the second half of the 20th century, the two terms were increasingly used interchangeably.
F.W. Aston used resolution as a binary variable and resolving power as a quantitative measure, for example, “the instrument will resolve beams of different masses if the change in ϕ for change of mass is greater than the geometrical spread, and the greater ϕ for a given mass and given spread the greater the resolving power” (Aston 1922). In his book Mass Spectra and Isotopes, Aston defines resolving power as M/ΔM (Aston 1933).
A. J. Dempster defined limit of resolution as Δm/m (Dempster 1918) and, like Aston, often used the construct “one in [mass]” for resolving power, as in “resolving power with this comparatively wide slit is 1 in 1000” (Dempster 1935).
K. T. Bainbridge stated that “resolving power is defined as the ratio M/ΔM for complete separation of two lines and so is more stringent than the optical definition” (Bainbridge 1936).
J. Mattauch defined resolving power as M/ΔM and resolution as ΔM/M (Mattauch 1936)
W. Bleakney used the term resolving power in a 1929 publication (Bleakney 1929) but defined resolution as m/Δm in a 1949 publication (Mariner 1949).
A. O. Nier used both resolving power (Nier 1936) as well as resolution (Nier 1960).
J. H. Beynon in his textbook Mass Spectrometry and its Applications to Organic Chemistry writes “’resolution’ and ‘resolving power’ have been used a great deal in the above discussion. It has been assumed that the doublet is ‘resolved’ when its constituent ion species are ‘separated’ and that the difficult of separation or ‘resolving power’ necessary to separate the adjacent mass peaks is given by M/ΔM” (Beynon 1960)
K. Biemann in his textbook Mass Spectrometry: Organic Chemical Applications, states that “the term resolution is used in different ways – Throughout this book resolution will be considered as M/ΔM” (Biemann 1962).
ASMS Definitions
Subcommittee 10 on Definitions and Terms of ASTM Committee E14 on Mass Spectrometry was established in 1970 and presented a compendia of terms at the 1974 ASMS meeting (Meyerson 1975). The ASMS Nomenclature Committee presented a list of terms at the 1982 ASMS meeting in Honolulu (Cameron 1982) and terms assembled by the ASMS Measurements and Standards Committee were published in 1991 (Price 1991) which closely paralleled the contemporary IUPAC recommendations (Todd 1991).
IUPAC Definitions
There have been four IUPAC recommendations for mass spectrometry terminology in the past five decades produced by the IUPAC Analytical Chemistry Division Commission on Analytical Nomenclature (Robertson 1974), the IUPAC Physical Chemistry Division Commission on Molecular Structure and Spectroscopy (Beynon 1978), the IUPAC Physical Chemistry Division Commission on Molecular Structure and Spectroscopy Subcommittee on Mass Spectroscopy (Todd 1991), and the IUPAC Physical and Biophysical Chemistry Division (Murray 2013). The IUPAC Compendium of Chemical Terminology “Gold Book” gives definitions of resolution (valley and width) from Todd 1991 and gives two conflicting definitions for resolving power, one from Todd 1991 (also Robertson 1974) that defines resolving power as Δm and one from Beynon 1978 that defines resolving power as m/Δm.
Recommendations
Terminology recommendations for resolution and resolving power must take into account the current interchangeable use of the terms as well as the longstanding use of resolving power as m/Δm. It is the opinion of the author that resolution should be used as a binary variable, resolving power defined as m/Δm be encouraged, and limit of resolution defined as Δm/m be used where necessary.
Resolution: The use of resolution as a quantitative measure is discouraged: use resolving power or limit of resolution as appropriate.
Resolving power: The observed m/z value divided by the smallest difference Δ(m/z) for two peaks that can be separated: (m/z)/Δ(m/z).
Limit of resolution: The smallest difference Δ(m/z) for two peaks that can be separated divided by m/z: Δ(m/z)/(m/z).
The recommendations above are those of the author who hopes that these concepts will be considered when developing the next list of terminology.
References
Aston, F.W.: Some problems of the massspectrograph. Philos. Mag. 43, 514 (1922)
Aston, F.W.: Mass Spectra and Isotopes, Arnold, London, (1933).
Bainbridge, K.T., Jordan, E.B.: Mass Spectrum Analysis. Phys. Rev. 50, 282 (1936)
Biemann, K: Mass Spectrometry: Organic Chemical Applications, McGrawHill, New York (1962).
Bleakney, W.: A New Method of Positive Ray Analysis and Its Application to the Measurement of Ionization Potentials in Mercury Vapor. Phys. Rev. 34, 157 (1929)
Beynon, J.H.: Recommendations for Symbolism and Nomenclature for Mass Spectroscopy. Pure Appl. Chem. 50, 65 (1978)
Beynon, J.H. Mass Spectrometry and its Applications to Organic Chemistry, Elsevier, (1960)
Cameron, D.: ASMS Nomenclature Committee Workshop. Annual Conference on Mass Spectrometry and Allied Topics Abstracts. 30, 901 (1982).
Dempster, A.J.: A new method of positive ray analysis. Phys. Rev. 11, 316 (1918)
Dempster, A.J.: New Methods in Mass Spectroscopy. Proc, Am. Phil. Soc. 75, 755 (1935)
Mariner, T., Bleakney, W.: A large mass spectrometer employing crossed electric and magnetic fields. Rev. Sci. Instrum. 20, 297 (1949)
Meyerson, S.: Definitions and terms in mass spectrometry. Biomed. Mass Spectrom. 2, 59 (1975)
Mattauch, J.: A DoubleFocusing Mass Spectrograph and the Masses of N15 and 018. Phys. Rev. 50, 617 (1936)
Murray, K.K., Boyd, R.K., Eberlin, M.N., Langley, G.J., Li, L., Naito, Y.: Definitions of terms relating to mass spectrometry, Pure. Appl. Chem. 85, 15151609 (2013)
Nier, A.O.: A MassSpectrographic Study of the Isotopes of Argon, Potassium, Rubidium, Zinc and Cadmium. Phys. Rev. 50, 1041 (1936)
Nier, A.O.: Small General Purpose Double Focusing Mass Spectrometer. Rev. Sci. Instrum. 31, 1127 (1960)
Price, P.: Standard definitions of terms relating to mass spectrometry. J. Am. Soc. Mass Spectrom. 2, 336 (1991)
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External links
 Urban, J., Afseth, N.K., Štys, D.: Fundamental definitions and confusions in mass spectrometry about mass assignment, centroiding and resolution. TrAC Trends in Analytical Chemistry. 53, 126136 (2014); http://dx.doi.org/10.1016/j.trac.2013.07.010