HIGH-PRESSURE CHEMICAL IONIZATION FLOW REACTOR FOR REAL-TIME MASS-SPECTROMETRIC DETECTION OF SULFUR GASES AND UNSATURATED-HYDROCARBONS IN AIR

A high-pressure selected-Ion chemical ionization flow reactor has been developed making real-time detection of atmospheric species possible at the subparts-per-trillon level when used in combination with a mass spectrometer or as a GC/MS interface. The ion chemistry in the reactor is well controlled due to the initial production of selected rectant ion species which form known product ions with the sample molecules. Wall effects are virtually eliminated by maintaining a laminar carrier gas flow in the reactor. The sensitivity achievable with this device has been demonstrated for the sulfur compounds CH3SCH3 and SO2 and for C15H24 (beta-caryophyllene), with detection limits of 0.5, 0.2, and 0.5 pptr, respectively.