Optimized ion mobility separation timescales for targeted ions
An analytical device for analysing 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 analysing ions comprising:
an ion mobility separator for separating ions according to ion mobility;
an interface, transfer device or region 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, transfer device or region; and
a control system arranged and adapted:
(i) to transmit a first group of ions which emerges from said ion mobility separator through said interface, transfer device or region with a first transit time t1; and
(ii) to transmit a second group of ions which subsequently emerges from said ion mobility separator through said interface, transfer device or region with a second different transit time t2, wherein t2>t1;
wherein the interface, transfer device or region is at the same pressure as the ion mobility separator.
2. An analytical device as claimed in claim 1 , wherein the control system is arranged and adapted to transmit the first group of ions which emerges from said ion mobility separator through said interface, transfer device or region with the first transit time t1 and to switch the analytical device so as to transmit the second group of ions which subsequently emerges from said ion mobility separator through said interface, transfer device or region with the second different transit time t2.
3. An analytical device as claimed in claim 1 , wherein the quadrupole rod set mass or mass to charge ratio filter switches between components of interest which elute from the ion mobility separator.
4. An analytical device as claimed in claim 1 , wherein the quadrupole rod set mass or mass to charge ratio filter is configured to switch between transmitting ions in the first group of ions and subsequently transmitting ions in the second group of ions, wherein the second transit time t2 is increased relative to the first transit time t1 so as to ensure that the second group of ions arrive at the mass filter after the mass filter has switched and has had time to settle such that the ions in the second group are transmitted by the mass filter.
5. An analytical device as claimed in claim 1 , comprising a collision, fragmentation or reaction cell.
6. An analytical device as claimed in claim 1 , comprising a Time of Flight mass analyser.
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 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.
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.
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. A mass spectrometer comprising an analytical device as claimed in claim 1 .
14. A method of analysing ions comprising:
providing an analytical device as claimed in claim 1 ;
separating ions according to ion mobility in the ion mobility separator;
transmitting a first group of ions which emerges from the ion mobility separator through the interface, transfer device or region with a first transit time t1; and
transmitting a second group of ions which subsequently emerges from the ion mobility separator through the interface, transfer device or region with a second different transit time t2, wherein t2>t1;
wherein the interface, transfer device or region is at the same pressure as the ion mobility separator.
15. A method of mass spectrometry comprising a method as claimed in claim 14 .
16. An analytical device for analysing ions comprising:
an ion mobility separator for separating ions according to ion mobility;
an interface, transfer device or region comprising one or more ion guides, each ion guide comprising a plurality of electrodes;
a quadrupole rod set mass to charge ratio filter arranged downstream of said interface, transfer device or region; and
a control system arranged and adapted:
(i) to transmit a first group of ions which emerges from said ion mobility separator through said interface, transfer device or region with a first transit time t1; and
(ii) to transmit a second group of ions which subsequently emerges from said ion mobility separator through said interface, transfer device or region with a second different transit time t2, wherein t2>t1;
wherein the quadrupole rod set mass to charge ratio filter is configured to switch between transmitting ions in the first group of ions and subsequently transmitting ions in the second group of ions, wherein the second transit time t2 is increased relative to the first transit time t1 so as to ensure that the second group of ions arrive at the mass filter after the mass filter has switched and has had time to settle such that the ions in the second group are transmitted by the mass filter.
17. An analytical device for analysing ions comprising:
an ion mobility separator for separating ions according to ion mobility;
an interface, transfer device or region comprising one or more ion guides, each ion guide comprising a plurality of electrodes, wherein the interface, transfer device or region is at the same pressure as the ion mobility separator; and
a control system arranged and adapted to apply different voltages to said interface, transfer device or region whilst ions are separated by the ion mobility separator, such that ions which emerge from said ion mobility separator at different times have different transit times through said interface, transfer device or region.
18. An analytical device for analysing ions, comprising:
an ion mobility separator for separating ions according to ion mobility;
an interface, transfer device or region comprising one or more ion guides, each ion guide comprising a plurality of electrodes;
a mass to charge ratio filter arranged downstream of said interface, transfer device or region; and
a control system arranged and adapted to apply different voltages to said interface, transfer device or region whilst ions are separated by the ion mobility separator, such that ions which emerge from said ion mobility separator at different times have different transit times through said interface, transfer device or region;
wherein the control system is configured to apply said different voltages to said interface, transfer device or region such that a first group of ions that emerges from the ion mobility separator arrives at the mass to charge ratio filter at a first time and is transmitted by the mass to charge ratio filter, and a second group of ions that emerges from the ion mobility separator arrives at the mass to charge ratio filter at a second, later time after the mass to charge ratio filter has switched and has had time to settle such that the ions in the second group are transmitted by the mass to charge ratio filter.