“…A number of approaches have been proposed to assess stability and the carbon sequestering potential of different biochars, including solid state nuclear magnetic resonance spectroscopy (solid state 13 C NMR) [13,14], thermal analysis (thermogravimetry, TG) [15,16], molecular markers by means of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) [17,18], benzene polycarboxylic acid method [19], O:C or H:C molar ratios [20,21], chemical oxidation [14,22], accelerated ageing technique [23], and hydropyrolysis (HyPy) [24,25,26].…”