A solid-state C-13 NMR analysis of ambers

Colombian copalite samples (found at 73 degrees 5'W 6 degrees 19'N in the C imitarra quadrangle), and commercial amber samples from Chiapas (Mexico), D ominican Republic and Poland (Baltic) were studied using solid-state C-13 C P-MAS Nuclear Magnetic Resonance (NMR), NMR spectra for Colombian amber are shown and compared to those reported for the resin from the genus of the A frican species Hymenaea verrucosa and other Hymenaea trees, for which a clo se resemblance is observed. NMR spectral features of the other studied ambe rs are also discussed. A physical aging experiment was performed on a Colom bian sample at 65 degrees C. Differences in the solid-state NMR and IR spec tra are explained in terms of changes in chemical cross-linking, isomerizat ion and morphology. (C) 1999 Elsevier Science Ltd. All rights reserved.