2.4.2. Step II: time-trend filtration
The component list obtained for each experiment was then processed with a routine written in Visual Basic for Applications(VBA), which is available as Supplementary Material. Firstly, the peak lists for the individual time steps were combined and the components within a ±5 mDa m/z and ±0.1 min RT window were grouped. A peak intensity curve was plotted for each specific com-ponent against time. To be flagged as a TP that is relevant within the scope of this study, we defined that a component had to followa meaningful time-trend, i.e. (1) it should be absent in the initial sample; (2) the intensity should increase continuously over sometime or the entire incubation period. Components fulfilling these criteria were retained for structure assignment.