ANALYTICAL PYROLYSIS AS A TOOL FOR THE CHARACTERIZATION OF ORGANIC-SUBSTANCES IN ARTISTIC AND ARCHAEOLOGICAL OBJECTS

The black solid content of a red ceramic bottle (Cyprus, XIV-XIIIth Century B.C.) and the organic patinas on the bronze statue of Neptune (Bologna, 1566 A.D.) were analyzed by pyrolysis-gas chromatography/mass spectrometry (PY-GC/MS) and by GC/MS after extractions with organic solvents, using a capillary gas chromatograph coupled to an Ion Trap Mass Spectrometer. Results show that the supposedly bituminous material of the ceramic bottle is, in fact, a mixture of aliphatic mono- and di-carboxylic acids, palmitic acid being the main peak, probably deriving from a vegetable oil. The patinas on the Neptune statue result in pyrograms containing mainly palmitic acid and minor quantities of other aliphatic acids, which can be attributed to both protective coatings and atmospheric depositions. Pyrolysis works as a thermal desorption injector and is useful for the rapid analysis of small samples.