I am trying to explain what happens to lignin before and after pyrolysis. The results of MALDI TOF for initial lignin shows a typical polymeric spectrum with periodic peaks with 24 m/z difference. However, this does not represent any repetitive structural unit as long as I know. For example there are four peaks corresponding to four units labeled as A, B, C and D which are repeating through out the spectrum. They each represent a specific unit though out our polymeric chain. See two pictures attached