View source for ASMS 1981

<code>Report on the ASMS Nomenclature Committee Workshops held at the 29th Annual Conference on Mass Spectrometry and Allied Topics, Minneapolis, Minnesota, May 24-29, 1981, 978-815</code>
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<big><big>'''ASMS Nomenclature Committee Workshops'''</big></big>

<big>Minneapolis, 1981 [https://www.asms.org/docs/default-source/proceedings-archive/1981_asms_29th_conference.pdf]</big>

__TOC__

Two workshops were held on Monday, May 25, 1981 and Thursday, May 28, 1981. 84 members attended the first Workshop and 35 members the second. A copy of the list of terms and definitions for use in mass-spectrometry that had.been prepared following last year's Workshop was distributed to each attendee. The list had already been circulated in advance to 50 people who had attended last year's Workshop or who had written request.ing that the list-be sent to them and their suggested modifications had been incorporated. 

Each term on the list was considered in detail. A copy of the terms finally approved at the workshops is attached.
 
Help was sought to prepare an additional list of terms for consideration at next year's Workshops. The following people volunteered to provide terms under the headings listed alongside their names 

:M.S. Story, Finnegan Instruments (Instrumentation detectors) 
:C.R. Lagergren, Battelle ([[Surface ionization]], [[thermal ionization]]) 
:M. Elliott, V.G. Ltd. ([[Isotope mass spectrometry]]) 
:F.A. Elder, Xerox Corporation ([[Knudsen cell mass spectrometry]]) 
:C.M: Judson, University of Kansas ([[Sample introduction]])

Several other people offered to send additional terms (with or without definitions) for inclusion in next year's list. 

(The deadline for receipt of terms by me is August 31, 1981. This will allow time for circulation of a new list of terms to the attendees at this year's Workshops so that their committees can be included, and preparation of an agreed list for discussion at the [[ASMS 1982|1982 Meeting in Hawaii]]). 

The following decisions were taken unanimously: 

l. That the.attached list of terms be submitted to the ASMS Board of Directors for their approval, with the following recommendations 

(i) That if the list is approved, it be considered 'provisional' for one more year so as to give all members a final opportunity of commenting upon it. 

(ii) That all comments received before December 31, 1981 be considered by the Chairman of the Nomenclature Committee who would then recommend  to the Board, in the light of such comments, which terms should be issued as ASMS recommended terms. 

{iii) That terms issued under the headings 'Vacuum' and 'Data System' should be separated into an Appendix to the list of recommended terms. 

(iv) That the generosity of the American Vacuum Society in providing most of the terms under the heading 'Vacuum' should be acknowledged in the list. 

2. That the same procedure as was used this year should be followed again so that a further list of terms can be submitted to the Board in a year's time.

::::::[[wikipedia:John H. Beynon|J .H. Beynon]]
::::::Chairman

::::::Royal Society Research Unit  
::::::University College of Swansea 
::::::Singleton Park, SWANSEA SA2 SPP, UK

==Ionization nomenclature ==
{{ASMS ionization nomenclature}}

==Other Terms==

;[[Mass analysis]] 
:A process by which a mixture of ionic or neutral species is identified according to the mass-to-charge (m/z) ratios (ions) or their aggregate atomic masses (neutrals). The analysis may be qualitative and/or quantitative. 

;[[Detection of ions]] 
:In mass spectrometry this concerns the observation of the arrival of particular ionic species, at a detector under conditions that preclude or minimize ambiguities due to interferences. Ions may be detected by photographic or suitable electrical means. 

;[[Scanning method]] 
:This term refers to the sequence of control over operating parameters of a mass spectrometer which results in a spectrum of masses, velocities, momenta or energies. 

;[[Sample introduction]] 
:This refers to the manner in which a material which is to be subject to analysis is placed in the ion source of a mass spectrometer before and/or during such an analysis. 

;[[Vacuum system]] 
:Those components used to lower the pressure within a mass spectrometer are all parts of the vacuum system. This includes not only the various pumping componentsbut also valves, gauges and associated electronic or other control devices, the chamber in which ions are formed and detected and the vacuum envelope. 

;[[Data system]] 
:The components used to record and process information during the analysis of a sample are part of the data system. This includes electronic or other control devices, and recording storage and data manipulation devices.
 
;[[Data processing]] 
:Once information is obtained with an appropriate data system, the information must be interpreted appropriate to the end use. Those steps which lead to this end use are of concern in data processing. Note that data processing does not necessarily include application of modern computer techniques. 

;[[Data reduction]] 
:The process of transforming the initial digital representation of a spectrometer output into a form which isn.amenable to interpretation; for example, a bar graph or a table of ion currents. 

;''[[m/z]]''
:This abbreviation is used to denote the dimensionless quantity formed by dividing the [[mass number]] of an ion by the number of charges carried by the ion. It has long been called the [[mass-to-charge ratio]] although ''m'' is not the ionic mass nor is ''z'' a multiple of the electronic charge, e-. The abbreviation ''m/e'' is, therefore, not recommended. Thus, for example, for the ion C<sub>7</sub>H<sub>7</sub><sup>2+</sup>, ''m/z'' = 45.5.

==Ion/molecule reactions== 
{{Ion/molecule reactions}}

==Scanning of Spectra== 
;[[Mass spectrum]] 
:A spectrum obtained when a beam of ions is separated according to the [[mass-to-charge ratio|mass-to-charge]] ([[m/z]]) ratios of the ionic species contained within it. 

:[Note : A [[quadrupole mass spectrometer]] achieves separation of the various ionic species in this way]. 

;[[Momentum spectrum]] 
:A spectrum obtained when a beam of ions is separated according to the [[momentum-to-charge ratio]]s of the ionic species contained within it. 

:[Note: A [[sector magnetic field]] achieves separation of the various ionic species in this way. If the ion beam is homogeneous in translational energy, as is the case with sector instruments, separation according to the ''m/z'' ratios is also achieved]. 

;[[Ion kinetic energy spectrum]] 
:A spectrum obtained when a beam of ions is separated according to the [[translational energy-to-charge ratio]]s of the ionic species contained within it. 

:[Note: A radial electric field achieves separation of the various ionic species in this way]. 

;[[Magnetic field scan]] 
:The usual method of producing a momentum (mass) spectrum in instruments. 

;[[Accelerating voltage scan|Accelerating voltage]] ([[high voltage scan|high voltage]]) scan 
:An alternative method of producing a momentum (mass) spectrum in [[magnetic deflection instrument]]s. This scan can also be used, in conjunction with a [[fixed radial electric field]] to produce an ion kinetic energy spectrum. 

;[[Linked scan]] 
:A scan, l'.n an" instrument comprising two or more analysers, in which two or more of the analyser fields are scanned simultaneously so as to preserve a predetermined relationship between parameters characterising these fields. often, these parameters are the field strengths, but may also be the frequencies in the case of analysers in which alternating fields are employed. 

;[[Linked scan at constant B/E]] 
:A linked scan at constant B/E may be performed on a sector instrument incorporating at least one magnetic sector plus one electric sector. It involves scanning the magnetic sector field-strength B and the electric sector field strength E simultaneously, holding the accelerating voltage V constant, so as to maintain the ratio B/E at a constant value. This constant value is determined by the ratio of the two field strengths which transmit main-beam ions of predetermined mass:charge ratio; these preselected [[main-beam ion]]s are the [[precursor ion]]s whose [[fragment-ion spectrum]] is required. The fragmentation reactions so observed occur in a [[field-free region]] traversed before the two sectors scanned in this way. 

:[Notes: This terms should not be used without prior explanation of the meanings of B and E. The term "[[B/E linked scan]]" is not recommended. It may suggest that the ratio B/E varies during the scan]. 

;[[Linked scan at constant E2/V|Linked scan at constant E<sup>2</sup>&sol;V]] 
:A linked scan at constant E<sup>2</sup>/V may be performed on a sector instrument incorporating at least one electric sector plus one magnetic sector. It involves scanning the electric sector field E and the accelerating voltage V simultaneously, so as to maintain the ratio E<sup>2</sup>/V at a constant value, equal to the value of this ratio which transmits the main beam of ions through the electric sector. The magnetic sector field is set at a fixed value such. that main-beam ions of a pre.determined mass:charge ratio are transmitted by the magnet; these preselected main.beam ions are the precursor ions whose fragment-ion spectrum is required. The fragmentation reactions so observed occur in a field-free region traversed before the two sectors scanned in this way.
 
:[Notes : This term should not be used without prior explanation of the meanings of E and V.
 
The term "[[E2&sol;V linked scan]]" is not recommended]. 

;[[Linked scan at constant B2/V|Linked scan at constant B<sup>2</sup>/V]] 
:A linked scan at constant B <sup>2</sup>/E may be performed on a sector instrument incorporating at least one electric sector plus one magnetic sector. It involves holding the accelerating voltage fixed, and scanning the magnetic field Band the electric field E simultaneously so as to maintain the ratio B<sup>2</sup>/E at a constant value. This constant value corresponds to the ratio of the two fields which 'transmit main-beam ions of predetermined mass:charge ratio; these preselected main-beam ions are the fragment ions whose precursor-ion spectrum is required. The fragmentationreactions thus observed occur in a field-free region traversed before the two sectors scanned in this way. 

:[Notes : This term should not be used without prior explanation of the meanings of Band E. The term "B2 /Elinked scan" is not recommended] . 

;Linked Scan at Constant B l[ (E/E0)]l /E A 1 inked scan at constant B[l -(Ee/E0)]'/E may be performed on a sector instrument incorporating at least one electric sector plus one magnetic sector. It involves holding the accelerating voltage fixed, and scanning the magnetic field B and electric field E simultaneously, so as to maintain the quantity B[l -(E/Eo)]l/E at a constant value. This constant value is equal to B3/E0 , where E0 and B3 are respectively the electric sector field and magnetic sector field required to transmit m; ions in the main ion-beam; me3 represents the mass (m1 - m2) of the selected neutral fragment whose precursor ion spectrum is required. The fragmentation reactions so observed occur in a field-free region traversed before the two sectors scanned in this way. 

:[Note: This term should not be used without prior explanation of the meanings of B, E and E<sub>0</sub>. 

;The term "B [1 -(E/E0)] '/E linked scan" is not recommended]. 
The above three definitions are merely examples of the types of linked scan that might
be used. Any other linked scans can readily be defined in a similar manner. 

;[[Fixed precursor ion scan]]s 
:1. Mass selection followed by ion kinetic energy analysis
If a precursor (parent) ion is selected, for example by a magnetic sector, all product ions formed from it in the field-free region between the magnetic sector and a following electric sector can be identified by scanning an ion kinetic energy spectrum. 
:2. Linked Scan at Constant B/E or at Constant E2/V
:Both of these linked scans give a spectrum of all product (daughter) ions formed from a preselected precursor (parent) ion. 

;[[Fixed product-ion scan]]s 
:1. [[High voltage scan]]. 
:2. Linked scan at constant B<sup>2</sup>/E. 

:Both 1. and 2. give. a spectrum of all precursor (parent) ions that fragment to yield a pre-selected product (daughter) ion. 

;[[Fixed neutral fragment scan]]s 
:1. The linked scan at constant B[l -(E.'E0)]'/E gives a spectrum of all product (daughter)ions that have been formed by loss of a pre-selected neutralfcagment from any precursor(parent) ions. 
[Note : The above definitions have all been given with reference to sector instruments; linked scans to give similar information have also been devised for instruments incorporating one or more quadrupoles]. 

;2E Mass spectrum processes of the partial charge-transfer type 

2+ + N+ 

m + N . m + 
occurring in a collision cell (containing a gas, N) located in a field-free region
preceding a magnetic and electric sector combination placed in either order, may be
detected as follows. 

If the instrument slits are wide, and if the electric sector field Eis set to twice the value required to transmit the main ion-beam, the only ions to be trans.mitted will be those with a kinetic energy/charge ratio twice, or almost exactlytwice, that of the main ion-beam. The product ions of the process shown fulfill this condition. If the magnetic field Bis scanned, a mass spectrum of such singly.charged product ions, and thus of their doubly-charged precursors, is obtained. Such a spectrum is called a 2E mass spectrum. 

;[[E/2 mass spectrum]] processes of the charge-stripping type 

m+ + N &rarr; m2+ + N + e-
occurring in a collision cell (containing a gas N) located in a field-free regionpreceding a magnetic and electric sector combination placed in either order, may be detected as follows. 

If the instrument slits are wide and if the electric sector field E is set to half the value required to transmit the main ion-beam, the only ions to be transmitted will be those with a kinetic energy/charge ratio half, or almost exactly half, that of the main ion-beam. The product ions of the charge-stripping process fulfill this condition. If the magnetic field B is scanned, a mass spectrum of such doubly-charged product ions, and thus of their singly-charged precursors, is obtained. Such a spectrum is called an E/2 mass spectrum. 

. [Note 
Interference from product ions from processes of the type 

+ 
m1 
+ 
-m2) 

where m2 . 0.5 m1, can arise in E/2 mass spectra].
 
;[[Charge inversion mass spectrum]] 
:Charge inversion processes of the types 

or m-+ N &rarr; m+ + N + 2e.

respectively, occurring in a collision cell (containing a gas, N) located in a field free region preceding a magnetic and electric sector combination placed in either order, may be detected as follows 

If the instrument slits are wide, and if the connections to the two sectors, appropriate to transmission of either positive or negative main-beam ions, are simply reversed, the negative or positive product ions of the two processes,respectively, will be transmitted. If the magnetic field is scanned, a spectrumof such product ions will be obtained, and this spectrum is called a charge-inversion mass spectrum. These spectra are sometimes referred to as -E and +Enspectra, respectively. 

:[Note : The terms "2E, E/2, -E or +E mass spectrum" should not be used without priorexplanation of the meaning of 2E, E, +E or -E]n.

[[category:reference]]