A plurality of targeted ion characteristics and a charge reduction amount are received. A subset of ionized molecules of a sample corresponding to each characteristic of the plurality of targeted ion characteristics is transmitted from a first location to a second location, producing a plurality of selected ionized molecules. Reagent ions are transmitted to the second location to reduce the charge state of the selected ionized molecules. The charge state reduction of the selected ionized molecules is stopped at the charge state reduction amount, producing a plurality of parked targeted ions in the second location. The targeted ion characteristics can include mobilities or mass-to-charge ratios. Quantitation information for an analyte can be obtained by performing targeted ion parking on a plurality of standards, developing a calibration function, performing targeted ion parking on a sample and using the calibration function to determine the concentration of the analyte in the sample.