Figure F1. A. Example of gas chromatogram showing strong odd–carbon number preference with clear peaks. B. Example of m/z 44 ion chromatogram for GC-IRMS analysis. Blue diamonds indicate internal standards for evaluation of carbon isotope values of long-chain n-alkanes.

Figure F1. A. Example of gas chromatogram showing strong odd–carbon number preference with clear peaks. B. Example of m/z 44 ion chromatogram for GC-IRMS analysis. Blue diamonds indicate internal standards for evaluation of carbon isotope values of long-chain n-alkanes.