Figure 3
Main results obtained from the ESI(-)-FTICR-MS analysis. (a) Mass spectrum (150–950 Da) of the Upper Gossan sample 010,109–1. Inset number in (a) represents the total number of assigned molecular members (i.e., CHO, CHNO and CHOS). (b) and (c) H/C ratio versus mass-to-charge (m/z) plot and van Krevelen diagram of all assigned molecular members, respectively (color-coded dots represent molecular members CHO, blue; CHNO, orange; and CHOS, green, while circular areas indicate relative mass peak intensity). Inset in (b) represents the frequency histogram of the exact mass differences corresponding to CH2, H2, On(1≤n≤5), NHn(1≤n≤3), and SOn(1≤n≤4) (error range 0.1 ppm). (d), (e) and (f) represent compound classes included in CHO, CHNO and CHOS-molecular members, respectively. Highlighted areas in (d), (e) and (f) visualize the following compound classes: (1) Saturated/unsaturated compounds, (2) Amino acids-/peptide-like compounds, (3) Carbohydrate-like compounds, and (4) highly unsaturated and aromatic compounds.
