2009 marked Hornbrook's first year with the Trace Organic Gas Analyzer (TOGA) team. Based out of NCAR, the TOGA team worked on creating instrumentation to improve the measurement of mixing ratios of different VOCs. In 2011, Hornbrook authored a paper detailing a new method to measure HO and RO while better separating the two differing compounds. The method proved to be effective at measuring VOCs and trace organic gases in both group based and airborne studies. The instrumentation dramatically increased the ability to detect trace organic gases by almost tripling the amount of compounds that are able to be measured.