“…Analysis of the raw PTR-MS data was performed as described by Siefarth et al (2011), converting transmission-corrected and normalized signal intensities of the product ions to volume mixing ratios (VMR) (de Gouw et al, 2003). The latter equilibrium concentrations of the flavor compounds were calculated with respect to a calibration curve, whereby the curve gradient indicates the sensitivity, ε (ncps ppb V −1 ), of the PTR-MS to a particular compound (Singer, Beauchamp, Herbig, Dunkl, & Kohl, 2007).…”