Optimised ion mobility separation timescales for targeted ions

1. An analytical device for analysing ions comprising:

a separator for separating ions according to a physico-chemical property;

an interface comprising one or more ion guides, each ion guide comprising a plurality of electrodes;

a quadrupole rod set mass or mass to charge ratio filter arranged downstream of said interface; and

a control system arranged and adapted:

(i) to transmit a first group of ions which emerges from said separator through said interface with a first transit time t 1 ; and

(ii) to transmit a second group of ions which subsequently emerges from said separator through said interface with a second different transit time t 2 .

2. An analytical device as claimed in claim 1 , wherein said physico-chemical property comprises ion mobility or differential ion mobility.

3. An analytical device as claimed in claim 2 , wherein said separator comprises an ion mobility separator or a differential ion mobility separator.

4. An analytical device as claimed in claim 1 , wherein said physico-chemical property comprises mass or mass to charge ratio.

5. An analytical device as claimed in claim 4 , wherein said separator comprises a time of flight region.

6. An analytical device as claimed in claim 1 , wherein said control system is arranged and adapted to transmit said second group of ions through said interface with a transit time t 2 , wherein t 2 >t 1 .

7. An analytical device as claimed in claim 1 , wherein said control system is further arranged and adapted to apply one or more transient DC voltages or potentials to said plurality of electrodes so that said first group of ions are translated along said one or more ion guides with a first velocity.

8. An analytical device as claimed in claim 7 , wherein said control system is further arranged and adapted to apply one or more transient DC voltages or potentials to said plurality of electrodes so that said second group of ions are translated along said one or more ion guides with a second different velocity.

9. An analytical device as claimed in claim 8 , wherein said second different velocity is slower than said first velocity.

10. An analytical device as claimed in claim 1 , wherein said control system is further arranged and adapted to maintain at a first time a first DC voltage or potential gradient along said one or more ion guides so that said first group of ions are urged along said one or more ion guides with a first velocity.

11. An analytical device as claimed in claim 10 , wherein said control system is further arranged and adapted to maintain at a second later time a second DC voltage or potential gradient along said one or more ion guides so that said second group of ions are urged along said one or more ion guides with a second different velocity.

12. An analytical device as claimed in claim 11 , wherein said second DC voltage or potential gradient is less than said first DC voltage or potential gradient.

13. An analytical device as claimed in claim 1 , wherein said control system is further arranged and adjusted:

(i) to cause said mass or mass to charge ratio filter to transmit ions having masses or mass to charge ratios within a first mass or mass to charge ratio range; and then

(ii) to cause said mass or mass to charge ratio filter to transmit ions having masses or mass to charge ratios within a second different mass or mass to charge ratio range.

14. An analytical device as claimed in claim 1 , wherein said control system is arranged and adapted to transmit said first group of ions which emerges from said separator through said interface with a first transit time t 1 and to transmit said second group of ions which subsequently emerges from said separator through said interface with a second different transit time t 2 within or during a single cycle of separation of ions within said separator.

15. A mass spectrometer comprising an analytical device as claimed in claim 1 .

16. A method of analysing ions comprising:

separating ions according to a physico-chemical property in a separator;

providing an interface comprising one or more ion guides, each ion guide comprising a plurality of electrodes and a quadrupole rod set mass or mass to charge ratio filter arranged downstream of said interface;

transmitting a first group of ions which emerges from said separator through said interface with a first transit time t 1 ; and

transmitting a second group of ions which subsequently emerges from said separator through said interface with a second different transit time t 2 .

17. A method as claimed in claim 16 , wherein the steps of transmitting said first group of ions which emerges from said separator through said interface with a first transit time t 1 and transmitting said second group of ions which subsequently emerges from said separator through said interface with a second different transit time t 2 are performed within or during a single cycle of separation of ions within said separator.

18. A method of mass spectrometry comprising a method as claimed in claim 16 .

19. An analytical device for analysing ions comprising:

a separator for separating ions according to a physico-chemical property;

an interface;

a quadrupole rod set mass or mass to charge ratio filter arranged downstream of said interface; and

a control system arranged and adapted:

(i) to transmit a first group of ions which emerges from said separator through a first ion path through said interface with a first transit time t 1 ; and

(ii) to transmit a second group of ions which subsequently emerges from said separator through a second different ion path through said interface with a second different transit time t 2 .

20. An analytical device as claimed in claim 19 , wherein said control system is arranged and adapted to transmit said first group of ions which emerges from said separator through a first ion path through said interface with a first transit time t 1 and to transmit a second group of ions which subsequently emerges from said separator through a second different ion path through said interface with a second different transit time t 2 within or during a single cycle of separation of ions within said separator.

21. A method of analysing ions comprising:

separating ions according to a physico-chemical property in a separator;

providing an interface and a quadrupole rod set mass or mass to charge ratio filter arranged downstream of said interface;

transmitting a first group of ions which emerges from said separator through a first ion path through said interface with a first transit time t 1 ; and

transmitting a second group of ions which subsequently emerges from said separator through a second different ion path through said interface with a second different transit time t 2 .

22. A method as claimed in claim 21 , wherein the steps of transmitting said first group of ions which emerges from said separator through a first ion path through said interface with a first transit time t 1 and transmitting a second group of ions which subsequently emerges from said separator through a second different ion path through said interface with a second different transit time t 2 are performed within or during a single cycle of separation of ions within said separator.