Characterization of copal incense from Mesoamerica: Identification of residues by GC-MS

CHED 280

Janine Van Gemert and Ruth Ann Armitage, rarmitage@emich.edu. Department of Chemistry, Eastern Michigan University, 225 Mark Jefferson, Ypsilanti, MI 48197
Copal, or pom, incense is widely used ritually and domestically in Mesoamerican cultures. The presence of copal residues in archaeological materials may help to place sites of unknown cultural affiliation into specific Mesoamerican contexts. Terpenoid compounds like abietic acid (and its many oxidation products) may be markers for the presence of copal in residues. We have undertaken gas chromatography-mass spectrometry (GC-MS) analysis of extracts from modern copal resins from Mexico and Guatemala to determine if burned residues of these materials retain the terpenoid marker compounds. Comparisons of the whole incense materials to residues from burning them were done using extraction in chloroform:methanol and derivatization to yield trimethylsilyl derivatives of the terpenoid compounds. TMS yielded cleaner chromatograms than did esterification with tetramethylammonium hydroxide. While many of the terpenoids were observed in the residues, burning occasionally induced significant changes. Further studies are needed to apply this method to archaeological materials.