Instrument assemblies including a support coupled to an active substrate are provided with the support being configured to be coupled to an interior portion of an ionization chamber. Instruments are also provided that can include a chamber being configured to contact at least a portion of a sample with an ionization species. The instruments can also include an active substrate within the chamber. Analysis methods are provided that can include providing a sample to a chamber and selectively retaining at least a portion of the first analyte of the sample within the chamber without retaining at least a portion of the second analyte within the chamber. Analysis methods can also include providing a sample to a chamber housing an active substrate, contacting at least a portion of the sample with the substrate, and ionizing the portion of the sample.