Linked scan
From Mass Spec Terms
| DRAFT DEFINITION |
| Linked scan |
|---|
|
A scan in an instrument with two or more m/z analysers or in a sector mass spectrometer that incorporates at least one magnetic sector and one electric sector. Two or more of the analyzers are scanned simultaneously so as to preserve a predetermined relationship between scan parameters to produce a product ion, precursor ion or constant neutral loss spectrum. |
| Considered between 2004 and 2006 but not included in the 2006 PAC submission |
| This is an unofficial draft definition presented for information and comment. |
Orange Book Entry
A scan in 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 characterizing these fields. While these parameters are commonly field strengths, they may also be frequencies in analysers where alternating fields are employed.
- This can be performed with a sector instrument incorporating at least one magnetic sector and one electric sector. The magnetic sector field strength, B, and the electric sector field strength, E, are scanned simultaneously, while holding the accelerating voltage, V, constant, so as to maintain the ratio B/E constant. This constant value is determined by the ratio of the two field strengths required to transmit main-beam ions of predetermined mass/charge ratio. These preselected main-beam ions are the precursor ions whose fragment ion spectrum is required. The term B/E linked scan is not recommended.
- This can be performed with a sector instrument incorporating at least one electric sector plus one magnetic sector. The magnetic sector field strength, B, and the electric sector field strength, E, are scanned simultaneously, while holding the accelerating voltage , V, constant, so as to maintain the ratio B [1- (E /E 0)]1/2 /E constant. This constant value is equal to B3/E0, where E0 and B3 are respectively the electric and magnetic sector fields required to transmit M3+ ions in the main ion beam; m3 represents the mass (m1-m2) of the selected neutral fragment M3 whose precursor spectrum is required. The fragmentation reactions thus observed occur in a field-free region traversed before the two sectors scanned in this way. The term 'B [1- (E /E 0)]1/2/E linked scan????????????????????????? is not recommended.
- This can be performed with a sector instrument incorporating at least one electric sector plus one magnetic sector. The accelerating voltage is fixed and the magnetic field, B, and the electric field, E, are scanned simultaneously so as to maintain B 2/E constant. This constant value corresponds to the ratio of the two fields which transmits mainbeam ions of predetermined mass/charge ratio; these preselected main-beam ions are the fragment ions whose precursor ion spectrum is required. The fragmentation reactions thus observed occur in a field-free region traversed before the two sectors scanned in this way. The term 'B 2/E linked scan????????????????????????? is not recommended. Note: other examples of linked scan should be defined in a similar way to the examples given here.
- This may be performed with a sector instrument incorporating at least one electric sector plus one magnetic sector. The electric sector field, E, and the accelerating voltage, V, are scanned simultaneously so as to maintain E 2/V ratio at constant value equal to the value of this ratio that transmits the main beam ions through the electric sector. The magnetic sector field is set at a fixed value such that main-beam ions of a predetermined mass/charge ratio are transmitted by the magnetic sector; these preselected main-beam ions are the precursor ions whose fragment ion spectrum is required. The fragmentation reactions thus observed occur in a field-free region traversed before the two sectors scanned in this way. The term 'E 2/V linked scan????????????????????????? is not recommmended.
