Fig. 2From: Rapid spilled oil analysis using direct analysis in real time time-of-flight mass spectrometryPositive ion heatmap of different types of oils shows the similarities of chemotypes of oil references within the same type. Heatmap also provides a tool to differentiate oils based on type, though some oil types are difficult to distinguish visually. Oil spectra are organized by type, indicated by the coloured lines above them and the legendBack to article page