Mass filter having extended operational lifetime

A mass and/or ion mobility spectrometer comprising:

• a first mass filter comprising a plurality of electrodes;
• a second mass filter comprising a plurality of electrodes arranged downstream of the first mass filter so as to receive ions transmitted by the first mass filter;
• a RF-only ion guide arranged between the first mass filter and the second mass filter so as to guide the ions transmitted by the first mass filter into the second mass filter, wherein the first mass filter, the second mass filter and the RF-only ion guide are located in a single vacuum chamber of the spectrometer;
• one or more voltage supplies;
• and
• a controller set up and configured to:
• control said one or more voltage supplies so as to apply voltages to the first mass filter so that it mass selectively transmits only ions having a first range of mass to charge ratios, wherein at least one of the electrodes of the first mass filter comprises an aperture extending entirely through the electrode and/or comprises a recess extending only partially through the electrode, wherein the aperture and/or recess is arranged and configured such that when said voltages are applied to the first mass filter ions become unstable in the first mass filter and pass into or through the aperture and/or into the recess such that they are not transmitted by the first mass filter to the second mass filter;
• and
• control said one or more voltage supplies so as to apply voltages to the second mass filter so that it mass filters the ions transmitted by the first mass filter, and such that the second mass filter only transmits ions having a second range of mass to charge ratios that is a sub-set of the first range of mass to charge ratios.

A mass and/or ion mobility spectrometer comprising:

• a first mass filter comprising a plurality of electrodes;
• a second mass filter comprising a plurality of electrodes arranged downstream of the first mass filter so as to receive ions transmitted by the first mass filter;
• a RF-only ion guide arranged between the first mass filter and the second mass filter so as to guide the ions transmitted by the first mass filter into the second mass filter, wherein the spectrometer is configured to maintain the first mass filter, the second mass filter and the RF-only ion guide at the same pressure;
• one or more voltage supplies;
• and
• a controller set up and configured to:
• control said one or more voltage supplies so as to apply voltages to the first mass filter so that it mass selectively transmits only ions having a first range of mass to charge ratios, wherein at least one of the electrodes of the first mass filter comprises an aperture extending entirely through the electrode and/or comprises a recess extending only partially through the electrode, wherein the aperture and/or recess is arranged and configured such that when said voltages are applied to the first mass filter ions become unstable in the first mass filter and pass into or through the aperture and/or into the recess such that they are not transmitted by the first mass filter to the second mass filter, and
• control said one or more voltage supplies so as to apply voltages to the second mass filter so that it mass filters the ions transmitted by the first mass filter, and such that the second mass filter only transmits ions having a second range of mass to charge ratios that is a sub-set of the first range of mass to charge ratios.