RECENT CHANGES IN AUTOMOTIVE PAINT FORMULATION USING PYROLYSIS-GAS CHROMATOGRAPHY MASS-SPECTROMETRY FOR IDENTIFICATION

The analysis of paint fragments recovered during forensic investigatio ns using Pyrolysis-GC/MS (PyGC-MS) has a long standing history. Pyrogr ams generated from intact fragments or separated layers are used to ma tch paint evidence to known paint formulations in an effort tb narrow the scope of the search, help identify involved vehicles, and exclude others. The peaks which appear in any pyrogram of an automotive paint may be a complex mixture of polymer pyrolysate, additives, plasticizer s and other ingredients, each of which has a specific function in the performance of the paint as a product. Automotive paint formulations u ndergo constant evolution and revision based on the needs of the indus try, including appearance, longevity, repair, and economics. Recently, environmental concerns have been added to the mix, with the mandate t o reduce volatile organic emissions from paints. Newer formulations ma y include a higher solids load, changed polymer chemistries, water-bas ed products and the results of other new technologies. How these formu lation changes present themselves when the dried paint is examined as forensic evidence is presented, together with comparisons of older for mulations. (C) 1997 Elsevier Science B.V.