Open Probe is based on a vaporization oven mounted on a transfer line of a gas chromatograph mass spectrometer (GC/MS) which is connected to the MS ion source via a short flow restriction capillary. The probe oven is open to room air while having helium purge flow protection to eliminate or significantly reduce air leakage into the oven and MS ion source. Sample analysis can be as simple as touch (the sample), push (the sample holder) into the open probe oven, and have the results. Experiments were performed with a GC/MS with supersonic molecular beams and with a standard Agilent 5975 MSD. Powders and tablets analysis were performed by touching the sample with the bottom side of a melting point vial and inserting it into the open probe oven with total analysis cycle time of <30 s. Similarly, trace trinitrotoluene (TNT) on human fingerprints was analyzed. Additional sample holder types included swabs, spoons, and vials. The open probe is a leak-proof MS probe which is characterized by fast analysis cycle time, and it uses a low cost mass spectrometer of GC/MS with the benefits of electron ionization of library search and uniform, quantitative response without ion suppression effects.