Journal: Rapid Communications in Mass Spectrometry

Article Title: Isotopologue Ratios Identify 13 C‐Depleted Biomarkers in Environmental Samples Impacted by Methane Turnover

doi: 10.1002/rcm.10118

Figure Lengend Snippet: The impact of variations during manual peak integration on the δ 13 C calculation for an archaeol standard (top panel) and 13 C‐depleted archaeol from an AOM‐influenced sediment sample from the Aceto Balsamico area of Guaymas Basin (Core 4992‐14, 4–6 cmbsf) (bottom panel), both detected as [M + NH₄] + adducts. Five integration approaches are shown, ranging from broader peak limits (left) to more narrowly focused on the central peak (right). Corresponding M1/M0 ratios and δ 13 C values in ‰ (Equations and ) are displayed below each peak, with minimal variation in δ 13 C values across all different peak integration approaches.

Article Snippet: Extracted ion chromatograms with an isolation width of ±5 to ±10 mDa were created for the M0 and M1 peaks of all targeted lipids and integrated using DataAnalysis 5.0 (Bruker Daltonics, Bremen, Germany).

Techniques:

Journal: Rapid Communications in Mass Spectrometry

Article Title: Isotopologue Ratios Identify 13 C‐Depleted Biomarkers in Environmental Samples Impacted by Methane Turnover

doi: 10.1002/rcm.10118

Figure Lengend Snippet: Comparison of δ 13 C values [‰] obtained from GC/irMS (blue diamonds) and reversed‐phase UHPLC/ESI/HRMS following Equations and for archaeol + NH₄ + and archaeol + H + (orange circles) across two sediment cores from the Guaymas Basin. The upper panels show data from the Cathedral Hill core (5000‐9), whereas the lower panels represent samples from the Aceto Balsamico core (4992‐14). To generate δ 13 C values from the UHPLC/HRMS data, we calculated the M1/M0 ratio using the peak area of the respective peaks and applied Equations and using a fixed δ H value of −234‰ (cf. Figure ). Error bars reflect the propagated error, combining δ H‐introduced uncertainty (±116‰) and the analytical standard deviation across multiple independent UHPLC/HRMS measurements, with n = X indicating the number of runs, fulfilling the following criteria: Only peaks with an integrated M0 area above 2 × 10 6 arb.u. and 5 × 10 6 arb.u. were included, depending on the applied LC separation methods after Wörmer et al. and Zhu et al. , respectively (cf. Figure ). Peaks showing signs of coelution, or oversaturation were excluded. A paired, non‐parametric Wilcoxon signed‐rank test indicated a statistically significant difference between δ 13 C values (average of replicates) derived from both adducts ( n = 20, V = 0, p = 1.91 × 10 −6 ) with a directional trend towards more 13 C‐depleted values found in the H + adduct of archaeol.

Article Snippet: Extracted ion chromatograms with an isolation width of ±5 to ±10 mDa were created for the M0 and M1 peaks of all targeted lipids and integrated using DataAnalysis 5.0 (Bruker Daltonics, Bremen, Germany).

Techniques: Comparison, Standard Deviation, Derivative Assay

Journal: Rapid Communications in Mass Spectrometry

Article Title: Isotopologue Ratios Identify 13 C‐Depleted Biomarkers in Environmental Samples Impacted by Methane Turnover

doi: 10.1002/rcm.10118

Figure Lengend Snippet: Horizontal strip plots of δ 13 C values in ‰, determined from M1/M0 ratios and following Equations and , for various lipids, detected in sediment core 5000‐9 (Cathedral Hill, Guaymas Basin; circles) and 4992‐14 (Aceto Balsamico, Guaymas Basin; squares), including diglycosidic archaeol (2G‐Archaeol), phosphatidylglycerol archaeol (PG‐Archaeol), phosphatidylinositol archaeol (PI‐Archaeol), phosphatidylglycerol hydroxyarchaeol (PG‐OH‐Archaeol), monoglycosidic hydroxyarchaeol (1G‐OH‐Archaeol), phosphatidylserine hydroxyarchaeol (PS‐OH‐Archaeol); phosphatidylethanolamine acyl ether glycerol (PE‐AEG‐C 33:2 ), acyletherglycerol (AEG‐C 35:0 ); ubiquinone‐8:8 (UQ‐8:8), phosphatidylcholine diacylglycerol C 32:1 (PC‐DAG‐C 32:1 ), phosphatidylcholine diacylglycerol C 32:1 (PC‐DAG‐C 32:1 ), triacylglycerol‐C 46:0 (TAG‐C 46:0 ), triacylglycerol‐C 48:0 (TAG‐C 48:0 ), ceramide (Cer) 18;02/16;0, pyropheophorbide a 27:2 sterylester, pyropheophytin a and hydroxypheophytin a . Metabolites are categorized, based on whether a direct or indirect connection to methane turnover has been reported (bottom), versus those with no conceivable association to methane biogeochemistry (top). The most abundant adduct for each compound was used for δ 13 C calculation. Datapoints represent individual UHPLC/HRMS measurements following Wörmer et al. for sediment samples along depth profiles (0–20 cm below seafloor at 2 cm intervals) that met the following conditions: M0 Peak area > 2 × 10 arb.u. (see Figure ), no coeluting peaks and no signs of detector oversaturation. The shaded region indicates the range of methanotrophic δ 13 C values reported in previous studies in environmental samples [ , , , , , , ], with the gray shaded region highlighting the range (−65‰ to −50‰), where source attribution must be nuanced due to the higher uncertainty of this approach.

Article Snippet: Extracted ion chromatograms with an isolation width of ±5 to ±10 mDa were created for the M0 and M1 peaks of all targeted lipids and integrated using DataAnalysis 5.0 (Bruker Daltonics, Bremen, Germany).

Techniques: Stripping Membranes, Environmental Sampling