The invention generally relates to methods for analyzing an analyte in a sample. In certain embodiments, the methods involve providing a capture module, the module configured to capture an analyte in a sample in an ambient environment and generate ions of the analyte, wherein the capture module comprises a cartridge and a porous substrate within the cartridge that is connected to a voltage source, and wherein the porous substrate further comprises an internal standard; capturing the analyte in the sample to the porous substrate of the capture module; generating ions of the analyte and the internal standard held by the porous substrate via the voltage source that is coupled to the porous substrate; and analyzing the generated ions of the analyte and the internal standard in a mass analyzer that is operably coupled to the capture module.