This proposal is for the continued development of a high-speed, high-gain preconcentrator that can dramatically improve the real-time air monitoring capabilities of mass spectrometers. Conventional preconcentrators produce high sensitivity to trace level constituents at the expense of long sampling times. The preconcentrator developed in Phase I uses novel desorption conditions to increase the concentration of the desorbed analyte in the carrier gas. As a result, it can provide high sensitivity with short sampling times. Phase I work clearly demonstrated the concept and included the construction and refinement of a prototype rapid-cycle preconcentrator. When operated in conjunction with an electron-impact ionization source, this preconcentrator produced enhancements in the ion signal greater than 500, compared with direct sampling, using a 3-second sampling time. We expect that this preconcentrator will enable mass spectrometers with traditional electron-impact ionization sources to detect in real-time contaminants at concentrations below 1 part per billion. The preconcentrator was also tested with a chemical ionization source. Phase II work will allow continued development of a low-pressure discharge chemical ionization source, that when combined with the preconcentrator, should yield real-time detection limits well into the part per quadrillion range.
