Matthew A. Covert

Disseminator for rapid, selectable, and quantitative delivery of low and semivolatile liquid species to the vapor phase

Nelson and Griggs [Rev. Sci. Instrum. 39, 927 (1968)] introduced a quantitative method for disseminating liquid samples to the vapor phase using a lead screw to depress the plunger of a syringe whose body was heated and whose ambient tip was placed into the flow of a carrier gas. In order to measure quantitative vapor-phase infrared spectra, we have modified a commercial device to improve the accuracy and precision for quantitative vapor delivery. Design changes have focused on disseminating reactive or low volatility liquids by heating only the syringe tip and dispensed liquid. Performance features include quantitative vapor-phase generation with greater than three orders of magnitude concentration range, including low volatility species, with most equilibration times <40s. The method has been vetted by comparing the derived gas-phase infrared data versus IR spectra taken using both gravimetric (National Institute of Standards Technology) and passive vapor generation (Pacific Northwest National Laborator...