Amber’s Chemical Links Revealed

Canadian Conservation Institute researchers have demonstrated that succinyl groups cross-link diterpene polymers to help tree resin solidify into amber (Anal. Chem. 2014, DOI: 10.1021/ac501073k). Well-known for its durable and insoluble nature, amber has preserved insects and plant material for millennia. But those same properties make the material difficult to analyze. Pyrolyzing samples to decompose them and then examining the residue using gas chromatography/mass spectrometry is the method of choice. In the new work, Jennifer A. Poulin and Kate Helwig altered the standard approach and heated samples more slowly to 450 °C rather than the usual 480 °C to reveal new details of the chemical structure of one class of amber. They confirm a four-decade-old proposal stating that in some ambers communyl or ozyl moieties of diterpene polymers are connected through succinyl ester links. The results suggest that succinic acid plays a key role in hardening plant resin into amber.