A system for analyzing one or more ion species of a sample including a first ion mobility filter associated with a first flow path for passing first ions of the sample, a second ion mobility filter associated with a second flow path for passing second ions of the sample, a first outlet from the first flow path for passing a portion of the first ions from the first flow path to the second flow path, and a first outlet from the second flow path for removing neutral particles from the second flow path where the first outlet from the second flow path is upstream of the second ion mobility filter in relation to the ion flow in the second flow path.