An instrument for separating ions may include an ion source configured to generate ions from a sample, at least one ion separation instrument configured to separate the generated ions as a function of at least one molecular characteristic and an electrostatic linear ion trap (ELIT) positioned to receive ions exiting the at least one ion separation instrument. The ELIT has first and second ion mirrors separated by a charge detection cylinder, and is configured such that an ion trapped therein oscillates back and forth through the charge detection cylinder between the first and second ion mirrors with a duty cycle, corresponding to a ratio of time spent by the trapped ion traversing the charge detection cylinder and total time spent by the trapped ion traversing a combination of the first and second ion mirrors and the charge detection cylinder during one complete oscillation cycle, of approximately 50%.