Figure 9

Base peak chromatograms of extracts from immediate or sequential metabolite capture. Extracts from a media blank, batch cultivation with immediate addition of XAD and batch cultivation with subsequent capturing of metabolites were measured in positive ionisation mode. The chromatogram of the media blank shows substances which are able to bind to the resin and prevent thereby binding of products and complicate further downstream processing. The batch cultivation where XAD was included illustrates that these substances are still present after the cultivation and can be only reduced when XAD16 is added at a very late time point when the media is already depleted as done in the repeated batch cultivation. The black arrow indicates the peak of the internal standard used for subsequent quantification.