Two dimensional MSMS
A method of mass spectrometry is disclosed comprising: performing a plurality of cycles of operation during a single experimental run, wherein each cycle comprises: mass selectively transmitting precursor ions of a single mass, or range of masses, through or out of a mass separator or mass filter at any given time, wherein the mass separator or mass filter is operated such that the single mass or range of masses transmitted therefrom is varied with time; and mass analysing ions.
1. A method of mass spectrometry comprising:
performing a plurality of cycles of operation during a single experimental run, wherein each cycle comprises: mass selectively transmitting precursor ions of a single mass, or range of masses, through or out of a mass separator or mass filter at any given time, wherein the mass separator or mass filter is operated such that the single mass or range of masses capable of being transmitted therefrom is varied with time; and
mass analysing ions;
wherein ions transmitted by the mass separator or filter in at least some of said cycles are fragmented or reacted to produce fragment or product ions, and wherein the method comprises varying the fragmentation energy or rate, or reaction energy or rate, during one or more of said cycles, or during said experimental run.
2. The method of claim 1 , comprising varying the fragmentation energy or rate, or reaction energy or rate, during one or more of said cycles.
3. The method of claim 2 , wherein the fragmentation energy or rate, or reaction energy or rate, varies with or in synchronism with the mass values transmitted by the mass separator or filter during a, or each, cycle.
4. The method of claim 1 , wherein the mass separator or filter is operated such that in each cycle the mass to charge ratio, or range of mass to charge ratios, capable of being transmitted therefrom is continuously scanned or stepped with time over a target range of mass to charge ratios.
5. The method of claim 1 , wherein the width of the range of masses that is capable of being transmitted by the mass separator or filter at any given time is varied during one or more of the cycles.
6. The method of claim 1 , comprising separating components of an analyte sample in a sample separation device, ionising the sample eluting from the sample separation device, and supplying the resulting ions to the mass separator or filter.
7. The method of claim 1 , wherein the sample separation device is a liquid chromatography device.
8. The method of claim 1 , wherein the different cycles have start and/or end masses that vary according to the elution time of the sample separation device.
9. The method of claim 1 , further comprising performing a calibration procedure that comprises:
performing said plurality of cycles of operation on a mixture including a plurality of standards to obtain mass spectral data;
processing the data using a peak detection algorithm;
matching detected mass peaks to theoretically expected mass peaks for the standards; and
constructing a mapping or calibration relationship between the mass to charge ratio values for the standards and the time of transmission of the standards by the mass separator or mass filter.
10. The method of claim 1 , comprising:
operating the method in a mode which performs a plurality of successive ones of said cycles whilst maintaining the collision energy or fragmentation rate, or reaction rate, constant and so as to cause fragmentation or reaction of the ions; and
operating the method in a mode which performs a plurality of successive ones of said cycles whilst maintaining the collision energy or fragmentation rate, or reaction rate, constant and so as to substantially not cause fragmentation or reaction of the ions.
11. The method of claim 1 , comprising:
operating a first mode in which ions transmitted by the mass separator or mass filter are fragmented or reacted, and mass analysing the resulting fragment or product ions;
operating a second mode in which the precursor ions transmitted by the mass separator or filter are substantially not fragmented or reacted, and mass analysing these ions;
switching to, or alternating between, the first and second modes in a single experimental run, wherein the switching or alternating between the first and second modes is synchronised with switching to new cycles of the plurality of cycles.
12. The method of claim 11 , wherein in the first mode, the ions transmitted by the mass separator or filter are fragmented with a collision energy or fragmentation rate, or are reacted at a reaction rate, that increases or decreases over each cycle.
13. The method of claim 1 , wherein different ones of said cycles at least partially overlap each other in time.
14. The method of claim 1 , wherein the mass filter is a quadrupole mass filter or other multipole mass filter; or wherein the mass separator or mass filter is an ion trap that mass selectively transmits ions of different masses downstream at different times during each cycle.
15. A mass spectrometer comprising:
a mass separator or mass filter;
a mass analyser; and
a controller arranged and adapted to control the spectrometer to perform a plurality of cycles of operation during a single experimental run, wherein each cycle comprises:
mass selectively transmitting precursor ions of a single mass, or range of masses, through or out of the mass separator or mass filter at any given time, wherein the mass separator or mass filter is operated such that the single mass or range of masses capable of being transmitted therefrom is varied with time; and
mass analysing ions in the mass analyser;
wherein ions transmitted by the mass separator or filter in at least some of said cycles are fragmented or reacted to produce fragment or product ions, and the fragmentation energy or rate, or reaction energy or rate, is varied during one or more of said cycles, or during said experimental run.
16. The mass spectrometer of claim 15 , wherein the controller is arranged and adapted to vary the fragmentation energy or rate, or reaction energy or rate, during one or more of said cycles, such that the fragmentation energy or rate, or reaction energy or rate, varies with or in synchronism with the mass values transmitted by the mass separator or filter during a, or each, cycle.
17. The mass spectrometer of claim 15 , wherein the controller is arranged and adapted to, during one or more of the cycles, vary the width of the range of masses that is capable of being transmitted by the mass separator or filter at any given time.
18. The mass spectrometer of claim 15 , wherein the controller is arranged and adapted to:
operate the mass spectrometer in a mode which performs a plurality of successive ones of said cycles whilst maintaining the collision energy or fragmentation rate, or reaction rate, constant and so as to cause fragmentation or reaction of the ions; and
operate the mass spectrometer in a mode which performs a plurality of successive ones of said cycles whilst maintaining the collision energy or fragmentation rate, or reaction rate, constant and so as to substantially not cause fragmentation or reaction of the ions.
19. The mass spectrometer of claim 15 , wherein the controller is arranged and adapted to:
operate the mass spectrometer in a first mode in which ions transmitted by the mass separator or mass filter are fragmented or reacted, and the mass analyser mass analyses the resulting fragment or product ions;
operate the mass spectrometer in a second mode in which the precursor ions transmitted by the mass separator or filter are substantially not fragmented or reacted, and the mass analyser mass analyses these ions; and
switch to, or alternate between, the first and second modes in a single experimental run, wherein the switching or alternating between the first and second modes is synchronised with switching to new cycles of the plurality of cycles.
20. The mass spectrometer of claim 19 , wherein in the first mode, the ions transmitted by the mass separator or filter are fragmented with a collision energy or fragmentation rate, or are reacted at a reaction rate, that increases or decreases over each cycle.