Analytical Chemistry Seminar
Analytical & Environmental Chemistry Division and Atmospheric Chemistry Program Seminar
Jointly sponsored by the Department of Chemistry and Biochemistry, CIRES, and the Environmental Program
Closing the loop on phase equilibrium: connecting fundamental volatility measurements of complex fluids with applications of headspace detection
by Megan Harries - Analytical division 3rd year student, Department of Chemistry and Biochemistry, University of Colorado Boulder
Almost all fluids that are useful to us are complex mixtures consisting of many components with differing properties. An understanding of the phase equilibrium of these fluids is essential to many scientific disciplines as well as industry. For example, knowledge gaps in this area affect applications ranging from the development of alternative fuels to the deployment of forensic methods based on vapor characterization. These applications depend on our ability to bridge the gap – governed by thermodynamics – between vapor and liquid composition. This is difficult for even a binary, but beyond a ternary mixture, it becomes a real hair-puller. To unite these two pieces of the complete picture, I am adapting two relatively new techniques: the advanced distillation curve (ADC) method for volatility measurement and PLOT-cryoadsorption for vapor sampling. A modification of the ADC method, in development, provides simultaneous determination of temperature, pressure, and the composition of both vapor and condensed phases of a fluid mixture, while PLOT-cryoadsorption provides the field-ready vapor analysis. I will present a preliminary study that demonstrates the method and our ability to reconcile the measurements with models. Finally, I will discuss two related projects demonstrating applications, one using ADC to evaluate two alternative fuels and the second demonstrating environmental applications of a field portable PLOT-cryoadsorption device.