A selection of 37 reference samples

A selection of 37 reference samples representative of four
different chemical families: terpenoids, proteins, polysaccharides,
and triglycerides such as respectively resins, glues, gums and oils
have been studied (supplementary Table 1s). We mainly focused on
the terpenoid resins (26 ofthe 37 references), and among our corpus,
three subfamilies can be sorted: diterpenic resins (copal, sandarac,
kauri, colophony, Venice turpentine); triterpenic ones (dammar,
elemi, mastic, frankincense) and shellacs made of sesquiterpenoids,
fatty acid derivatives and anthraquinone dyes [35]. It is important to
note that the di-or triterpenoid proportion is generally a minor part
of the resins, the major one being the polymerized fraction [36].