Method of operating a mass filter in mass spectrometry

A mass spectrometer comprising:

• an ion source for producing ions;
• a mass filter for transmitting ions from the ion source;
• a discontinuous ion optical device downstream of the mass filter for processing ions received from the mass filter, wherein the processing comprises discontinuously transmitting ions;
• a mass analyser downstream of the discontinuous ion optical device for mass analysing ions that have been processed by the discontinuous ion optical device, wherein a duration of processing ions with the discontinuous ion optical device is exceeded by a duration of analysing ions in the mass analyser, wherein a plurality of idle times are defined between periods in which the discontinuous ion optical device is processing ions;
• and,
• a controller arranged to operate the mass filter for a plurality of periods in a mass/charge ratio (m/z) filtering mode to transmit ions in one or more selected ranges of m/z to the discontinuous ion optical device and to operate the mass filter in a broad mass range mode transmitting ions of a mass range substantially wider than any mass range transmitted in the m/z filtering mode during the idle times, whereby during idle times ion deposition on surfaces of the mass filter is reduced compared to during periods when the mass filter is operated in the mass/charge ratio (m/z) filtering mode.

A method of mass spectrometry comprising:

• transmitting ions from an ion source through a first mass filter and subsequently through a second mass filter;
• providing a discontinuous ion optical device downstream of the second mass filter for processing ions received from the second mass filter;
• operating at least one of the mass filters for a plurality of periods in a mass/charge ratio (m/z) filtering mode to transmit ions in one or more selected ranges of m/z to the discontinuous ion optical device;
• analysing ions in a mass analyser downstream of the discontinuous ion optical device that have been processed by the discontinuous ion optical device, wherein a duration of processing ions with the discontinuous ion optical device is exceeded by a duration of analysing ions in the downstream mass analyser, wherein a plurality of idle times are defined between periods in which the discontinuous ion optical device is processing ions;
• and,
• operating the mass filter in a broad mass range mode transmitting ions of a mass range substantially wider than any mass range transmitted in the m/z filtering mode during the idle times, whereby during the idle times ion deposition on surfaces of the mass filter is reduced compared to during the periods when the mass filter is operated in the mass/charge ratio (m/z) filtering mode.

A method of mass spectrometry comprising:

• transmitting ions from an ion source through a mass filter;
• providing a mass analyzer downstream of the mass filter for processing ions received from the mass filter;
• operating the mass filter for a plurality of periods in a mass/charge ratio (m/z) filtering mode to transmit ions in one or more selected ranges of m/z to the mass analyzer;
• analysing ions in the mass analyser downstream of the discontinuous ion optical device that have been processed by the discontinuous ion optical device, wherein a duration of processing ions with the discontinuous ion optical device is exceeded by a duration of analysing ions in the downstream mass analyser, wherein a plurality of idle times are defined between periods in which the discontinuous ion optical device is processing ions;
• and
• operating the mass filter in a broad mass range mode transmitting ions of a mass range substantially wider than any mass range transmitted in the m/z filtering mode during the idle times, whereby during the idle times ion deposition on surfaces of the mass filter is reduced compared to during the periods when the mass filter is operated in the mass/charge ratio (m/z) filtering mode.