Mass spectrometer and method
A charge detection mass spectrometer, CDMS, is described. The CDMS comprises: an electrostatic sector field ion trap and an inductive charge detector, wherein the electrostatic sector field ion trap is configured to define, at least in part, an ion path via the inductive charge detector; and a fragmentation device. A method is also described.
1 . A charge detection mass spectrometer (CDMS) comprising:
an electrostatic sector field ion trap and an inductive charge detector, wherein the electrostatic sector field ion trap comprises a set of electrostatic sectors, including a first electrostatic sector and a second electrostatic sector, wherein the first electrostatic sector and the second electrostatic sector are mutually spaced apart by a field-free region traversed by an ion path, wherein the inductive charge detector is disposed in the field-free region, and wherein the electrostatic sector field ion trap is configured to define, at least in part, the ion path via the inductive charge detector;
a fragmentation device; and
an ion isolating optical element configured to isolate a precursor ion for fragmentation by the fragmentation device.
2 . The CDMS according to claim 1 , wherein the electrostatic sector field ion trap is configured to move an ion around the ion path defined,
wherein moving the ion induces signals in the inductive charge detector, and
wherein the CDMS is configured to determine a mass to charge ratio and a charge of the ion using the induced signals, and to determine the mass of the ion based on the determined mass to charge ratio and charge.
3 . The CDMS according to claim 2 , wherein the CDMS is configured to determine a mass of a precursor ion and the fragmentation device is configured to fragment the same precursor ion.
4 . The CDMS according to claim 1 , wherein the electrostatic sector field ion trap is configured to define, at least in part, the ion path via the fragmentation device.
5 . The CDMS according to claim 1 , further comprising means for ejecting ions from the ion path into the fragmentation device, wherein the fragmentation device is external to the electrostatic sector field ion trap.
6 . The CDMS according to claim 5 , wherein the electrostatic sector field ion trap comprises an ion outlet for exit of ejected ions therethrough from the ion path.
7 . The CDMS according to claim 1 , wherein the fragmentation device is configured to trap the precursor ion and/or a product ion thereof.
8 . The CDMS according to claim 1 , wherein the fragmentation device is configured to increase an ion energy of the product ion to be introduced into the ion path.
9 . The CDMS according to claim 7 , wherein the fragmentation device is configured to introduce the product ion into the ion path by pulsing the product ion into the ion path.
10 . The CDMS according to claim 1 , wherein the ion isolating optical element comprises and/or is a quadrupole lens, an einzel lens, a deflection plate; and/or is provided by the electrostatic sector field ion trap; or a combination thereof.
11 . The CDMS according to claim 1 , wherein the electrostatic sector field ion trap is isochronous.
12 . The CDMS according to claim 1 , wherein the ion path defined by the electrostatic sector field ion trap includes a crossover.
13 . The CDMS according to claim 1 , wherein the electrostatic sector field ion trap comprises an ion inlet for introduction of ions therethrough into the ion path.
14 . The CDMS according to claim 1 , wherein the inductive charge detector comprises a first set of charge detector tubes, including a first charge detector tube, optionally—wherein the first charge detector tube, having a length L and a width W, has a ratio of the length L to the width W in a range from 3:2 to 5:2, for example 2:1.
15 . The CDMS according to claim 1 , comprising a set of electrostatic focus lenses, including a first focus lens, arranged to constrain, at least in part, the ion path in a first dimension, preferably—wherein the first dimension is orthogonal to a direction of the ion path via the inductive charge detector.
16 . The CDMS according to claim 1 , wherein the inductive charge detector is configured to operate at ground potential.
17 . The CDMS according to claim 1 , comprising a lift device configured to increase an ion energy of ions to be introduced into the ion path, and wherein the lift device is configured to trap the ions to be introduced into the ion path.
18 . A method of determining masses of ions, the method comprising:
providing a charge detection mass spectrometer comprising an electrostatic sector field ion trap and an inductive charge detector, wherein the electrostatic sector field ion trap comprises a set of electrostatic sectors, including a first electrostatic sector and a second electrostatic sector, wherein the first electrostatic sector and the second electrostatic sector are mutually spaced apart by a field-free region traversed by an ion path, wherein the inductive charge detector is disposed in the field-free region, and wherein the electrostatic sector field ion trap is configured to define, at least in part, the ion path via the inductive charge detector;
moving, by the electrostatic sector field ion trap, a precursor ion around the ion path defined, at least in part, thereby, via the inductive charge detector;
inducing, by the moving precursor ion, a signal in the inductive charge detector;
determining a mass of the precursor ion using the induced signal;
fragmenting the isolated precursor ion and providing a product ion therefrom; and
determining a mass of the product ion.