Method of operating a multipole device

A method of operating a multipole device comprising a first pair of opposing electrodes and a second pair of opposing electrodes, the method comprising:

• sorting a list of mass-to-charge ratios that are assigned to one of a first polarity configuration and a second polarity configuration by an assigned polarity configuration, the first polarity configuration being a configuration in which a first polarity DC offset is applied between the first and second pairs of opposing electrodes, and the second polarity configuration being a configuration in which a second, opposite polarity DC offset is applied between the first and second pairs of opposing electrodes;
• and
• based on the sorting, operating the multipole device for a first time duration according to the first polarity configuration to select ions having mass-to-charge ratios from the list that are assigned to the first polarity configuration and operating the multipole device for a second time duration, distinct from the first time duration, according to the second polarity configuration to select ions having mass-to-charge ratios from the list that are assigned to the second polarity configuration.