A comparison of analytical techniques and the products formed during the decomposition of biodiesel under accelerated conditions

► Biodiesel was oxidised over 360 h at 90 °C and 150 °C. ► NMR, GC-MS, UV-VIS, FT-IR, rheology and RI were used to assess the products formed. ► NMR and GC-MS give most information, in situ FT-IR is the best technique for a sensor. ► Products identified include epoxides, ketones, acids, esters, alcohols and aldehydes. ► Low temperatures give a lower viscosity though the same amount of FAME decomposed.