Optimised ion mobility separation timescales for targeted ions
An analytical device for analyzing ions is provided comprising a separator 2 for separating ions according to a physico-chemical property and an interface 3 comprising one or more ion guides. A quadrupole rod set mass filter 4 is arranged downstream of the interface 3 . A control system is arranged and adapted: (i) to transmit a first group of ions which emerges from the separator 2 through the interface 3 with a first transit time t1; and (ii) to transmit a second group of ions which subsequently emerges from the separator 2 through the interface 3 with a second different transit time t2.
1. An analytical device for analyzing ions comprising:
a separator for separating ions according to a physico-chemical property and comprising a transfer region,
said transfer region comprising a plurality of electrodes;
a quadrupole rod set mass or mass to charge ratio filter arranged downstream of said transfer region; and
a control system arranged and adapted:
(i) to transmit a first group of ions through said transfer region with a first transit time t1; and
(ii) to transmit a second group of ions through said transfer region with a second different transit time t2,
wherein said control systems is further arranged and adapted to:
maintain at a first time a first DC voltage or potential gradient along said transfer region so that said first group of ions are urged along said transfer region with the first transit time t 1 , and
maintain at a second later time a second DC voltage or potential gradient along said transfer region so that said second group of ions are urged said transfer region with the 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 apply a shift or increase in transit time for the second group of ions through said transfer region.
7. An analytical device as claimed in claim 6 , wherein said shift or increase in transit time is introduced by altering the parameters of said separator.
8. 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 transfer region with a first velocity.
9. An analytical device as claimed in claim 8 , 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 transfer region with a second different velocity.
10. An analytical device as claimed in claim 9 , wherein said second velocity is slower than said first velocity.
11. An analytical device as claimed in claim 8 , wherein said physico-chemical property comprises ion mobility, and said separator comprises an ion mobility separator.
12. An analytical device as claimed in claim 1 , 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 through said transfer region with a first transit time t1 and to transmit said second group of ions through said transfer region with a second different transit time t2 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. 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 transfer region with a transit time t2, wherein t2>t1.
17. A method of analysing ions comprising:
separating ions according to a physico-chemical property in a separator comprising a transfer region comprising a plurality of electrodes;
providing a quadrupole rod set mass or mass to charge ratio filter arranged downstream of said transfer region;
transmitting a first group of ions through said transfer region with a first transit time t 1 ;
transmitting a second group of ions through said transfer region with a second different transit time t 2 ;
maintaining at a first time a first DC voltage or potential gradient along said transfer region so that said first group of ions are urged along said transfer region with the first transit time t 1 ; and
maintaining at a second later time a second DC voltage or potential gradient along said transfer region so that said second group of ions are urged along said transfer region with the second, different transit time t 2 .
18. A method as claimed in claim 17 , wherein the steps of transmitting said first group of ions through said transfer region with a first transit time t1 and transmitting said second group of ions through said transfer region with a second different transit time t2 are performed within or during a single cycle of separation of ions within said separator.