Fig. 3.

Incubation of amber beads under various biologically relevant conditions. a Beads were removed from necklaces and sorted into colour variants, then stored at 37 °C in either pH 5.5 PBS or octanol for 6 months. Bead supernatants were periodically collected and succinic acid content was analysed by HPLC. b Succinic acid was only detected in the supernatant of light-coloured beads stored in octanol, in which one of three replicates had significantly fragmented and degraded