Methods included in the trial included approaches based on biomarkers, particularly benzene
polycarboxylic acids (BPCA). Chemical oxidative treatments using acid dichromate or sodium
chlorite were represented; other oxidative approaches used ultra-violet treatment (photooxidation)
with correction for non-black aromatic carbon through 13C NMR analysis of
oxidised residues. A chemo-thermal oxidation method used a temperature threshold of
375°C, also with 13C NMR and elemental analysis of residues. A purely thermal (gravimetric)
analysis was represented using a helium gas flow containing 20% oxygen. Purely
spectroscopic methods included thermal or optical laser transmittance and reflectance, and
mid-infrared. Additional methods assessed were matrix assisted laser desorption ionisation
(MALDI –TOF) and hydrogen pyrolysis.