Method of characterising molecules by ion-mobility spectrometry

1. A method of identifying and/or characterising ions, the method comprising:

separating analyte ions according to a first physico-chemical property;

selecting first ions of the analyte ions, and activating, fragmenting or reacting the first ions to produce first product ions;

separating the first product ions according to the first physico-chemical property, and determining a pattern of the first product ions; and

identifying and/or characterising the first ions using the pattern of the first product ions.

2. The method of claim 1 , wherein the first physico-chemical property comprises ion mobility or rate of change of ion mobility with electric field strength.

3. The method of claim 1 , wherein:

the analyte ions, the first ions and/or the first product ions are polymeric; and/or

the analyte ions, the first ions and/or the first product ions are isomeric.

4. The method of claim 1 , wherein the analyte ions comprise isomeric polymeric analyte ions of a particular order, and the first product ions comprise polymeric product ions of a plurality of different orders, each order of the plurality of different orders being less than the particular order of the isomeric polymeric analyte ions.

5. The method of claim 4 , wherein the pattern of the first product ions comprises, in respect of one or more or each order of the plurality of different orders, the number of isomers of that order that are present in the first product ions.

6. The method of claim 1 , wherein characterising the first ions using the pattern of the first product ions comprises determining structural information of the first ions from the pattern of the first product ions.

7. The method of claim 1 , further comprising:

selecting second ions of the analyte ions, and activating, fragmenting or reacting the second ions to produce second product ions;

separating the second product ions according to the first physico-chemical property, and determining a pattern of the second product ions; and

identifying and/or characterising the first and/or second ions using the pattern of the second product ions.

8. The method of claim 7 , further comprising comparing the pattern of the first product ions with the pattern of the second product ions, and identifying and/or characterising the first and/or second ions on the basis of the comparison.

9. The method of claim 1 , further comprising:

selecting particular ions of the first product ions, and activating, fragmenting or reacting the particular ions to produce second generation product ions; and

separating the second generation product ions according to the first physico-chemical property, and determining a pattern of the second generation product ions;

wherein the pattern of the first product ions includes the pattern of the second generation product ions.

10. The method of claim 1 , comprising separating the analyte ions according to the first physico-chemical property using a cyclic or closed-loop separator and separating the first product ions according to the first physico-chemical property using the cyclic or closed-loop separator.

11. A mass and/or ion mobility spectrometer, comprising:

one or more activation, collision, fragmentation or reaction devices;

one or more separators; and

a control system, wherein the control system is configured:

to cause the one or more separators to separate analyte ions according to a first physico-chemical property;

to cause first ions of the analyte ions to be selected, and to cause the one or more activation, collision, fragmentation or reaction devices to activate, fragment or react the first ions to produce first product ions;

to cause the one or more separators to separate the first product ions according to the first physico-chemical property;

to determine a pattern of the first product ions; and

to identify and/or characterise the first ions using the pattern of the first product ions.

12. The spectrometer of claim 11 , wherein the first physico-chemical property comprises ion mobility or rate of change of ion mobility with electric field strength.

13. The spectrometer of claim 11 , further comprising an ion source configured to generate the analyte ions;

wherein the analyte ions, the first ions and/or the first product ions are polymeric; and/or

wherein the analyte ions, the first ions and/or the first product ions are isomeric.

14. The spectrometer of claim 11 , wherein:

the analyte ions comprise isomeric polymeric analyte ions of a particular order, and the first product ions comprise polymeric product ions of a plurality of different orders, each order of the plurality of different orders being less than the particular order of the isomeric polymeric analyte ions.

15. The spectrometer of claim 14 , wherein the control system is configured to determine the pattern of the first product ions by:

determining, in respect of one or more or each order of the plurality of different orders, the number of isomers of that order that are present in the first product ions.

16. The spectrometer of claim 11 , wherein the control system is configured to characterise the first ions using the pattern of the first product ions by determining structural information of the first ions from the pattern of the first product ions.

17. The spectrometer of claim 11 , wherein the control system is configured:

to cause second ions of the analyte ions to be selected, and to cause the one or more activation, collision, fragmentation or reaction devices to activate, fragment or react the second ions to produce second product ions;

to cause the one or more separators to separate the second product ions according to the first physico-chemical property;

to determine a pattern of the second product ions; and

to identify and/or characterise the first and/or second ions using the pattern of the second product ions.

18. The spectrometer of claim 11 , wherein the control system is configured:

to cause particular ions of the first product ions to be selected, and to cause the one or more activation, collision, fragmentation or reaction devices to activate, fragment or react the particular ions to produce second generation product ions; and

to cause the one or more separators to separate the second generation product ions according to the first physico-chemical property; and

to determine a pattern of the second generation product ions;

wherein the pattern of the first product ions includes the pattern of the second generation product ions.

19. The spectrometer of claim 11 , wherein the one or more separators comprise a cyclic or closed-loop separator.

20. A computer readable medium storing software code, which when executing on a processor, causes the processor to perform a method of identifying and/or characterising molecules, the method comprising:

determining a pattern of first product ions, the first product ions being produced by separating analyte ions according to a first physico-chemical property, selecting first ions of the analyte ions and fragmenting or reacting the first ions to produce the first product ions; and

identifying and/or characterising the first ions using the pattern of the first product ions.