Determining an expected response of a mass spectrometer

A non-transitory computer-readable medium comprising instructions which, when executed by a processor of an apparatus, cause the apparatus to perform a method of determining an expected response to injecting a beam of ions of a species of interest into a static field mass filter of a mass spectrometer comprising a mass analyser, the method comprising:

• for each species of a plurality of test ion species:
• causing a beam of ions of the species to be injected into the static field mass filter;
• and
• for each of a plurality of test magnetic field strengths of the static field mass filter;
• setting the magnetic field to the test magnetic field strength;
• for each of a plurality of test electric field strengths of the static field mass filter:
• setting the electric field to the test electric field strength;
• and
• measuring, using the mass analyser, an intensity of ions of the species in the beam for the test magnetic field strength and the test electric field strength;
• determining a first electric field strength of the plurality of test electric field strengths at which the measured intensity has reached a peak intensity;
• determining a second electric field strength of the plurality of test electric field strengths at which the measured intensity has reached a first predetermined fraction of the peak intensity, the second electric field strength being higher than the first electric field strength;
• determining a third electric field strength of the plurality of test electric field strengths at which the measured intensity has reached a second predetermined fraction of the peak intensity, the third electric field strength being lower than the first electric field strength;
• and
• based on a first predetermined relationship between magnetic field strength, electric field strength and centre mass of the static field mass filter, determining a first lower mass corresponding to the second electric field strength and the test magnetic field strength and determining a first higher mass corresponding to the third electric field strength and the test magnetic field strength;
• interpolating, from the first lower mass for each of the plurality of test ion species and for at least one of the test magnetic field strengths, a first lower expected mass for an ion species of interest using a first interpolant function;
• and
• interpolating, from the first higher mass for each of the plurality of test ion species and for the at least one of the test magnetic field strengths, a first higher expected mass for the ion species of interest using a second interpolant function.

A non-transitory computer-readable medium comprising instructions which, when executed by a processor of an apparatus, cause the apparatus to perform a method of determining, for a target ion mass, a bandpass range of an ion filter for a mass spectrometer, the method comprising:

• introducing at least two ion species into the ion filter;
• scanning a mass range of each ion species by changing at least one filter parameter;
• determining an ion intensity associated with each scanned mass using the mass spectrometer;
• registering the ion intensities and the associated filter parameters of each scanned mass range;
• for each scanned mass range, determining a maximum ion intensity and the associated centre mass;
• for each scanned mass range, determining:
• a first mass associated with a first ion intensity corresponding with a first fraction of the respective maximum intensity, and
• a second mass associated with a second ion intensity corresponding with a second fraction of the respective maximum intensity,
• wherein the first mass is lower than the centre mass of the ion species and the second mass is higher than the centre mass of the ion species;
• and
• for the target ion mass having a known centre mass, deriving the masses having the associated first ion intensity and second ion intensity from the determined first ion intensities and second ion intensities of the scanned masses.