Charge filter arrangement and applications thereof

A charge filter instrument, comprising:

• an electric field-free drift region having an inlet end and an outlet end opposite the inlet end, the inlet end configured to be coupled to an ion source to receive a plurality of ions to drift axially through the drift region and separate from one another as a function mass-to-charge ratio as the plurality of ions drift from the inlet end toward the outlet end, the plurality of ions including ions having charge states or charge magnitudes different from others of the plurality of ions,
• a plurality of spaced-apart charge detection cylinders disposed in the drift region and through which the plurality of ions drifting axially through the drift region pass,
• a plurality of charge sensitive amplifiers each coupled to at least one of the plurality of charge detection cylinders and each configured to produce a charge detection signal corresponding to a magnitude of charge induced thereon by a single ion passing therethrough or by a combination of multiple ions simultaneously passing therethrough,
• one of a charge deflector having a single inlet coupled to the outlet end of the drift region and a single outlet, and a charge steering device having a single inlet coupled to the outlet end of the drift region and multiple outlets,
• at least one processor, and
• at least one memory having instructions stored therein and executable by the at least one processor to cause the at least one processor to
• (a) determine edge events and signal magnitudes of the charge detection signals, the edge events defined by rising and falling edges of each of the charge detection signals and the signal magnitudes defined between respective edge events of each charge detection signal,
• (b) for each of the plurality of ions drifting axially through the field-free drift region, (i) process the edge events of the charge detection signal produced by each successive one of the plurality of charge sensitive amplifiers to identify entrance of the ion into and exit of the ion from a respective one of the charge detection cylinders, (ii) between each successive entry and exit of the ion into and from a respective one of the charge detection cylinders, process the signal magnitude of the respective charge detection signal to determine the charge magnitude or charge state of the ion, and (iii) update the determination of the charge magnitude or charge state of the ion with each successive determination of the charge magnitude or charge state of the ion based on the respective one of the charge detection signals, and
• (c) for each of the plurality of ions exiting the outlet end of the drift region, control the one of the charge deflector and the charge steering device so as to pass through a corresponding one of the single outlet and a specified one of the multiple outlets only ions having a determined charge magnitude or charge state equal to, or within a specified range of, a specified charge magnitude or charge state.