Further, the mass filter can be adapted to be operable to transmit only ions having a mass within a mass window around a predefined mass, wherein the width of the mass window is selected based on the ion mass range transmitted by the mass analyser to the multicollector. The width of the mass window preferably is not greater or substantially greater than the range of ion masses detected in parallel by the multicollector.

The mass filter can be adapted to be operable to (i) transmit only ions having a mass within a first mass window during a first time period in which the mass analyser is set to transmit ions of a first analysis mass range to the multicollector, the first mass window being selected based on the first analysis mass range. The mass filter can also (ii) transmit only ions having a mass within a second mass window during a second time period, following the first time period, in which the mass analyser is set to transmit ions of a second analysis mass range to the multicollector, the second mass window being selected based on the second analysis mass range, wherein the second analysis mass range is different to the first analysis mass range.

The quadrupole mass filter can be adapted to transmit a single mass with a mass window of at most 0.9 amu, preferably at most 0.8 amu and most preferably at most 0.7 amu.

A filter can be provided for removing non-ionic species, the filter being arranged upstream from the mass filter.