Dr. Hornbrook is an expert in the measurement and scientific analysis of ambient gas-phase VOC mixing ratios, and is a member of the VOC Measurements Group that deploys trace gas instrumentation on airborne platforms. She has been integral in the development, deployment, data reduction, and scientific analysis of observations using NSF NCAR Trace Organic Gas Analyzer (TOGA) instrumentation, fast online gas chromatography/mass spectrometers, including the TOGA-TOF with an electron impact high-resolution time-of-flight mass spectrometer.