Figure 2.

Percent mass change across the GC × GC–FID chromatogram throughout the experiment, calculated based on the average chromatogram at each time point in the experiment relative to the average chromatogram at day 0 (the average chromatogram is the average of the three replicate chromatograms). To limit noise, only the pixels representing the largest 10% in the day 0 chromatogram are displayed (the remaining 90% of pixels were shaded black), and smoothing was added to the data using a smoothing window of 2 and 10 pixels in the first and second dimensions. The general locations of selected constituents or constituent groups are indicated based on previous literature^22,59 and on standard elution times, although it should be noted that other constituents may also occur within the defined constituent groups (see Methods S8 and Table S3, Supporting Information). Note: due to the smoothing applied, naphthalene and naphthalene-d8 overlapped, such that their mass losses are not accurate (naphthalene-d8 is not an oil constituent).