A method of inhibiting the reaction between ions of opposite polarity is disclosed. The method includes exposing a population of ions to a resonance excitation frequency during a mass-to-charge altering reaction between a first subpopulation of ions and a second subpopulation of ions, the resonance excitation frequency being tuned to inhibit the mass-to-charge altering reaction between an ion of the first subpopulation of ions having a predetermined mass-to-charge ratio and an ion of the second subpopulation of ions so that when an ion of the first subpopulation of ions attains the predetermined mass-to-charge ratio, the ion having the predetermined mass-to-charge ratio is selectively inhibited from reacting with ions of the second subpopulation of ions.