Difference between revisions of "Resolving power (in mass spectrometry)"

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Measure of the ability of a mass spectrometer to provide a specified value of mass resolution.
 
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Latest revision as of 01:50, 7 April 2014

IUPAC RECOMMENDATIONS 2013
Resolving power (in mass spectrometry)
mass resolving power

Measure of the ability of a mass spectrometer to provide a specified value of mass resolution.

Note: The procedure by which Δ(m/z) was defined and measured, and the m/z value at which the measurement was made, should be reported.
Related Term(s):
Reference(s):

Revised from

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). On-line 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 on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins.

From Definitions of Terms Relating to Mass Spectrometry (IUPAC Recommendations 2013); DOI: 10.1351/PAC-REC-06-04-06 © IUPAC 2013.

Index of Recommended Terms

 




Orange Book

ORANGE BOOK DEFINITION

IUPAC. Analytical Division. Compendium of Analytical Nomenclature (the Orange Book). Definitive Rules, 1979.

Resolving power (in mass spectrometry)

The ability to distinguish between ions differing in the quotient mass/charge by a small increment. It may be characterized by giving the peak width, measured in mass units, expressed as a function of mass, for at least two points on the peak, specifically for 50% and for 5% of the maximum peak height.

IUPAC 1997 Orange Book Chapter 12
Index of Orange 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).

Resolving power (in mass spectrometry)

Resolving power (mass spectrometry)

http://goldbook.iupac.org/R05321.html

The ability to distinguish between ions differing in the quotient mass/charge by a small increment. It may be characterized by giving the peak width, measured in mass units, expressed as a function of mass, for at least two points on the peak, specifically at fifty percent and at five percent of the maximum peak height.

mass resolving power

http://goldbook.iupac.org/M03730.html

Commonly and also acceptably defined in terms of the overlap (or 'valley') between two peaks. Thus for two peaks of equal height, masses and , when there is overlap between the two peaks to a stated percentage of either peak height (10% is recommended), then the resolving power is defined as . The percentage overlap (or 'valley') concerned must always be stated.

Source: PAC, 1978, 50, 65 (Recommendations for symbolism and nomenclature for mass spectroscopy) on page 72

IUPAC Gold Book
Index of Gold 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/PAC-REC-06-04-06 © 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, McGraw-Hill, 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, Lippincott-Raven, 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, Wiley-IEEE, 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, Wiley-Interscience, 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, Svein-Ole Mikalsen, Wiley-Interscience, 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, Hans-Rudolf H??pker, Wiley, 2008, ISBN 3527319417

Early manuscripts defining resolution and/or resolving power

F. Aston, Bakerian lecture. "A new mass-spectrograph 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) 956-959. 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) 157-160. 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 a-Containing Papers of a Mathematical and Physical Character, 140 (1933) 535-543. 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) 755-767. 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).

Resolving power (in 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).

Resolving power (in mass spectrometry)
http://goldbook.iupac.org/P04465.html

peak resolution, Rs (in chromatography)

The separation of two peaks in terms of their average peak width at base (t R2 > t R1):

R s = t R2 ? t R1 w b1 + w b2 2 = 2 ( t R2 ? t R1 ) w b1 + w b2

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:

R s = t R2 ? t R1 w b2

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).

Resolving power (in 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:

RAB = 2(|dR(B)-dR(A)|)/(|wB+ wA|)

where RAB is the resolution, dR (A) and dR (B) are the retention distances (time or volume) of each eluted component A and B, and wA and wB 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).

Resolving power (in 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 mass-to-charge 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)

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 E-14 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 mass-spectrograph. 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, McGraw-Hill, 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 Double-Focusing 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, 1515-1609 (2013)

Nier, A.O.: A Mass-Spectrographic 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)

Robertson, A.J.B.: Recommendations for Nomenclature of Mass Spectrometry. Pure Appl. Chem. 37, 469 (1974)

Todd, J.F.J.: Recommendations for Nomenclature and Symbolism for Mass-Spectroscopy. Pure. Appl. Chem. 63, 1541 (1991)