The Owlstone FAIMS device operates as a selective ion filter; how well the sensor detects a particular gas depends on the ionization source used. We currently have UV and Nickel ionisation options.
Nickel Ionization

With a Nickel ionization source a gas will be easily ionized and detected if it has a higher proton affinity than other background gases.
UV Ionization

With a UV ionization source ions will be generated if the gas has an ionisation energy less than 10.6eV.
If you have a specific request for a gas please contacts us at sales@owlstone.co.uk