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Dr. Tara M. Lovestead
Brief
Tara M. Lovestead received a B.S. in nutrition at Virginia Tech (1997), and a M.S. and Ph.D. in chemical engineering from the University of Colorado at Boulder (2002, 2004). Her dissertation research was on crosslinking polymer reaction kinetics, mechanism, and material properties. She continued her polymers research as a postdoc at the University of New South Wales. There she applied her knowledge of non-classical polymer reaction kinetics to improving the control of living polymerizations and the development of well-defined polymer systems. Her current research is on alternative fuels, energetic materials (explosives) and the forensic applications of analytical chemistry. The author of over 40 scientific publications, she is currently a National Academy of Sciences / National Research Council postdoctoral associate at NIST. Her current research interests include alternative fuels, energetic materials, and forensic applications of analytical chemistry. Dr. Lovestead enjoys rock climbing and camping with her husband, and dog when she is not in the lab. She has recently added a baby boy to her family. He, too, is toted along to outdoor adventures.
Research Interests:
Alternative Fuels
Application of the Advanced Distillation Curve Method to the Development of Alternative Fuels.
Interest in the domestic production ofallfuels, sparked by the high cost of petroleum crude oil, has led to consideration of fluids to replace or extend conventional petroleum-derived fuels. Because of the complexity offuels and especially alternative fuels, analytical characterization methods are limited. The advanced distillation curve (ADC) method is a significant improvement over classical distillation curve approaches, especially for complex fluids. The ADC method uses temperature, volume, and pressure measurements of low uncertainty, providing true thermodynamic state points that can be modeled with an equation of state, greatly aiding in the design of new fuels.In addition, the advanced distillation curve method incorporates a composition-explicit data channel, allowing for precise qualitative identification as well as quantitative analyses of each distillate fraction. This method also affords an assessment of the energy content of each distillate fraction, among other features. The most significant modification is achieved with an on-the-fly sampling approach that allows precise qualitative as well as quantitative (even trace) analyses of each distillate fraction. We have used this method to measure a variety of complex fluids, including theaviation gasoline avgas 100LL and alternative unleaded aviation gasolines,rocket propellants, thehypersonic propellant JP-7, a biodiesel fuel derived fromcuphea and soybean oil, anddiesel fuel blends with a variety of oxygenate additives.
Vapor Characterization
"Trace Headspace Sampling for Quantitative Analysis of Explosives with Cryoadsorption on Short Alumina PLOT Columns"
One way to detect explosive materials is to examine the headspace for the presence of the energetic compounds or additives. For example, explosive materials are often mixed with taggants (materials added intentionally for identification), which are more volatile than the explosive materials, and thus, more facile to detect. To aid in explosive material detection, we characterized the headspace air above several energetic materials. We used the newly developed method ofcryoadsorptionin combination with activated porous layer open tubular (PLOT) columns to collect the compounds in the headspace above real explosives. After headspace collection, the analytes were separated, identified, and quantified with gas chromatography and mass spectrometric detection (GC-MS). Headspace measurements have been performed on the pure explosive compound TNT, the practical military explosives C-4, Semtex-A and Semtex-H (plastic explosives), detonator cord (lead azide) and detonator sheet. This work has been published inAnalytical Chemistry.
Related article: Bruno, T.J., Simple, Quantitative Headspace Analysis by Cryoadsorption on a Short Alumina PLOT Column, J. Chromatogr. Sci., 47, 5069-5074, 2009.
"Detecting hydrogen peroxide permeation through polymeric barriers"
We developed a novel apparatus and method for detecting and quantifying the permeation of trace quantities of hydrogen peroxide (H2O2) through polymer barriers (i.e., plastic bottles). H2O2 has been used to make improvised explosives or incendiary weapons that resemble a bottled drink. An analytical method developed by the Transportation Security Laboratory (DHS) that utilizes fluorescence detection was implemented in our laboratory. Measurements were performed with 35 and 50 % H2O2. The polymer barriers used were obtained from common food and beverage containers. We observed an increase in the hydrogen peroxide concentration in the chamber that was initially 100 % water. This increase can be used to track H2O2 permeation through the polymeric barrier and the dependence of polymer type and thickness on H2O2 permeation.
The permeation cell apparatus was also used to test the permeation of H2O2 vapor through polymer barrier. For this experiment,the bottom chamber was only filled one-half way withH2O2 solution. The top chamber was sealed with ambient air. The top chamber's headspacewas sampledat different time pointsby use of a fused silicacapillary columnthatwas inserted through the septum to deliver a flow of carrier (or sweep) gas at constant pressure (0.1-0.5 psi) to the top chamber. Another fused silica capillary column was also inserted through the septum to allow the carrier gas (and any solutes in the headspace) to pass out of the top chamber, to flow through the column, and to bubble intothereagentthat generates the fluorescent compound in the presence ofH2O2. We were, in fact, able to observetrace quantities of hydrogen peroxidevaporpermeation through the polymeric barrier. The permeation of hydrogen peroxide (liquid and vapor) through polymeric barriers can be used to detect bottle bombs with minimal or no direct human contact.
Forensic Applications of Analytical Chemistry
"Sensitive, quantitative detection of trace volatile compounds for forensic applications"
The separations and detection methods developed forexplosive materials detectionin this laboratory are also being used to detect volatile fire retardants in automobile interiors, in the development of metrologies to monitor food spoilage, (detection of poultry spoilage markers) and indetecting grave soilto aid law enforcement personal in locating clandestine graves.The method can be used in the laboratory or as a field sampling technique. It provides a simple and inexpensive sample collection method with no compromise in efficiency or increased uncertainty. Moreover, the ability to obtain reproducible, quantitative measurements is a significant advantage over other approaches.