Dr. Widegren attended The Colorado College and graduated with a B.A. in chemistry. During the summers he did undergraduate research on photocatalytic oxidations with Professor John L. Falconer in the Chemical Engineering Department at the University of Colorado. His graduate studies were done in the Chemistry Department at Colorado State University with Professor Richard G. Finke. His Ph.D. thesis focused on the synthesis and catalytic properties of metal nanoparticles. After graduate school, he spent a year as a visiting professor at Adams State University, where he taught classes in general and analytical chemistry. He began his career at NIST with NRC and PREP Postdoctoral Fellowships, during which he studied the thermophysical properties of ionic liquids with postdoctoral advisor, Dr. Joseph W. Magee. He is currently the NMR Facility Manager for NIST Boulder and the Group Safety Representative for the Fluid Characterization Group. Dr. Widegren is part of a research team at NIST that received the Innovations in Measurement Science Award, with funding to develop spectroscopic measurements of intermolecular interactions in solution. He is part of other research teams that are developing reference materials and measurement services to improve breath tests of disease and intoxication. Away from work, he enjoys gardening, beekeeping and traveling.
Research Areas:
Developing reference materials and measurement services for breath metrology
The primary goal of this work is to improve breath tests for disease and forensic drug detection. One focus area is the validation of technology related to diagnosing two important infectious diseases, tuberculosis and malaria. We are developing methods to deliver breath biomarkers of these diseases in gas mixtures that match the major features of exhaled breath in terms of composition, temperature, and humidity. The final delivered mixtures, referred to as breath surrogates, will enable breath sampling devices and sensors to be evaluated in a controlled laboratory setting. This work is a collaboration with the Gas Sensing Metrology Group (Chemical Sciences Division) and is being done in partnership with the Gates Foundation.
Another focus area is the validation of breath tests for drug molecules like tetrahydrocannabinol (THC), the psychoactive compound in cannabis. A key difficulty in the development of this type of “breathalyzer” technology is that molecules like THC are present at very low concentrations in exhaled breath (ppb to ppt levels). A related issue is that, because of the low vapor pressures of target molecules like THC, these molecules may be carried out of the lungs in breath aerosols, instead of being in the vapor phase like ethanol. Breath aerosols are sub-micrometer fluid particles that are formed from the lining of the lung by the mechanical action of breathing. Most commercial breath sampling devices have been designed to collect this aerosol phase for later analysis. Currently, there is no standardized method to test the efficacy of such breath aerosol collection devices. Thus, we are developing an aerosol delivery system for drugs and toxicology applications that will generate a reproducible size distribution of aerosol particles, with a known number density and a known concentration of drug molecule in the aerosol.
Expanding the metrological applications of NMR spectroscopy
NMR spectroscopy is best known as a tool for chemical structure determination. Its use for quantitative measurements is promising but much less studied. In broad terms, Dr. Widegren’s current research with NMR spectroscopy involves the development of methods that improve (i) the measurement of NMR signal intensities for amount-of-substance determinations and (ii) the measurement NMR signal frequencies for equilibrium and solvation measurements. Some recent focus areas include low-uncertainty gas-phase mixture analysis, analysis of mixed-phase (gas + liquid) samples, measurements of ion-pairing equilibrium in solution, chemical shift referencing at high pressures, and measurements in which temperature, pressure, and mixture composition are determined simultaneously. A few real-world applications of these methods include the development of next-generation refrigerant mixtures for heating/cooling, improvement of battery performance, and more reliable determination of protein structure.
Improving vapor pressure measurements on large molecules
In simple terms, vapor pressure is the tendency of a liquid or solid to evaporate (turn into a gas). In general, the larger a molecule is, the lower its vapor pressure. Very few vapor pressure measurements are available for molecules with more than about 15 non-hydrogen atoms because such molecules are usually not sufficiently stable to withstand the slow, hot measurement process. One focus of Dr. Widgren’s work in this area is the optimization of apparatus design and measurement methodology so that low-uncertainty measurements on large molecules can be made quickly, thus avoiding problems with thermal stability. Our recently invented vapor pressure measurement method, called dynamic vapor microextraction (DVME), is being used to measure compounds of importance for breathalyzer development. For example, we have measured vapor pressures for cannabinoids such as THC (the psychoactive component of cannabis) and cannabis-associated terpenes like linalool. Such vapor pressure data are a key to designing breath sampling devices and to developing reference materials for breath analysis.
Additional areas of expertise
Dr. Widegren has worked in several additional research areas during his career. These include water content measurements (Karl Fischer titration, NMR spectroscopy), thermal stability measurements on organic compounds, enthalpy of adsorption measurements, permeation studies, thermophysical properties of ionic liquids, fluid property measurements (including density, viscosity, speed of sound, and electrolytic conductivity), homogeneous and heterogeneous catalysis with transition metals, nanoparticle synthesis and characterization, organometallic synthesis and characterization, inert atmosphere manipulations (glove box and vacuum line), and photocatalysis.
● American Chemical Society Colorado Section Award (2023)
● American Chemical Society Editor’s Choice Award (2023)
● NIST Material Measurement Laboratory Mentor Award (2022)
● Innovations in Measurement Science Award, NIST (2020)
● Material Measurement Laboratory Outreach Award (2018)
● NIST Safety Award (2010)
● PREP Postdoctoral Fellowship, University of Colorado/NIST (2005)
● National Academy of Sciences/National Research Council (NAS/NRC) Postdoctoral Fellowship (2003)
● Union Carbide Corporation's Student Innovation Recognition Award (2001)
● Merck Award for the outstanding chemistry graduate, Colorado College (1994)