PRECONCENTRATOR/CI SOURCE FOR QMS OF TRACE GASES IN AIR

THIS RESEARCH WILL DESIGN AND CONSTRUCT THE PREPROTOTYPE OF AN ULTRASENSITIVE ION SOURCE THAT CAN BE EASILY INTERFACED TO QUADRUPOLE MASS SPECTROMETERS FOR REAL-TIME TRACE CONSTITUENT DETECTION. THE DESIGN WILL BE BASED ON THE COMBINATION OF PRECONCENTRATION AND RECOMBINATION-LIMITED, LOW-PRESSURE AIR CHEMICAL IONIZATION (AIR-CI) CONCEPTS. THE GAIN IN CONCENTRATION OF TRACE CONSTITUENTS GENERALLY DEPENDS UPON THE DURATIONS, PRESSURES, AND GAS-FLOW RATES OF THE SAMPLING AND PURGE PHASES. UNLIKE A CONVENTIONAL PRECONCENTRATOR THAT USES ONLY TIME PARAMETERS TO INCREASE THE CONCENTRATION OF CONSTITUENTS, THE NEW PRECONCENTRATOR WILL UTILIZE BOTH PRESSURE AND TIME PARAMETERS. THE CONCENTRATED TRACE CONSTITUENTS WILL BE IONIZED BY USING AN APPROPRIATE AIR-CI SOURCE THAT OPERATES AT A PRESSURE OF ABOUT 10 TO 30 TORR. THIS UNIQUE COMBINATION OF A PRECONCENTRATOR AND MATCHING AIR-CI SOURCE WILL RESULT IN ANULTRASENSITIVE ION SOURCE FOR MASS SPECTROMETERS.