A gas detection system for selectively detecting one or more gases from a mixture of gases includes a gas sensor that includes at least one graphene field effect transistor (GFET). The GFET includes a source electrode, a drain electrode, a graphene channel layer, a gate electrode arranged proximate the graphene channel layer, and a dielectric layer between the graphene channel layer and the gate electrode. The gas detection system also includes a modulation system electrically connected to the gate electrode to modulate a response of the GFET to the gas sample, a detector electrically connected to the source electrode and the drain electrode to detect a modulated signal containing information concerning a response of the GFET to the gas sample during modulation by the modulation system, and a signal processor configured to communicate with the detector to receive the modulated signal. The signal processor is further configured to selectively determine a concentration of at least one gas in the gas sample base
