Flushing IMS cell between IMS cycles

摘要

A method and apparatus separates ions temporally according to a physico­chemical property, which may be mobility, differential mobility, mass or mass-charge ratio (m/z), purges unwanted ions from an ion guide. There may be two modes of operation, the first mode separating ions according to ion mobility and the second mode ejecting unwanted ions after ions of interest have left the ion guide. The flushing of residual ions may comprise changing either the velocity or the amplitude of the transient voltage in the ion guide, or changing the gradient of the voltage difference across the ion guide. The amplitude may be increased in the purging mode, or the velocity may be reduced. The relative duration of the first mode and the second mode may be adjustable. Alternatively, a deflection voltage, or a pulse of purging substance, such as gas, may be applied to the ion guide. The system may serve to reduce wrap-around or aliasing effects.