| Summary: | 碩士 === 中央警察大學 === 鑑識科學研究所 === 87 === It's an important clue to investigate traffic cases, associated with hit-and-run by the examinations of tiny paint chips. The major difficulties deriving from procedures for the effective determination of trace paints always encountered forensic scientists. This study is placed on the identification and comparison of those trace topcoat paints of original automotives with pyrolysis-GC/MS and Micro/FTIR, especially included selecting optimum conditions of the pyrolysis-GC/MS procedure and sampling trace paints with specific methods. Results indicate that the bigger paint could be adhered to a slide with super glue, and scrape about 100 μg the topcoat with No. 11 surgical knife handled under a very low angle. Based on the complementary identification of binders using Micro/FTIR, 12 basecoats having partially different binder systems were classified by the characteristic monomers derived from pyrolysates. 7 clearcoats with same acrylic/melamine binders were no doubt to be discriminated by comparisons of relative intensities of monomers and extra minor or trace additives. Py-GC/MS has been proved to be more effective than Micro/FTIR for the determination of binders having similar copolymers. Smear samples could to be differentiated as two different binder paints composed of up to 95:5. In practice, the combination of the two techniques of pyrolysis-GC/MS and Micro/FTIR is strongly recommended as a means of providing reliable identification and comparison of trace paints.
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