運用熱裂解氣相層析質譜分析法對於車漆成分定量之研究

Abstract

複雜的車漆樣品雖可藉由傅立葉轉換紅外線光譜儀（FTIR）、熱裂解氣相層析質譜儀（Pyrolysis-GC/MS）等方式加以定性，而定量的目標似乎遙不可及，最主要的原因在於變數多不易掌握，尤其是固體且經聚合後的高分子樣品，基質複雜性高，增加了困難度。本研究嘗試針對樣品量的多寡設計出二種不同的定量方式；當樣品量多時以熱重分析法（Thermogravimetry，TG）結合熱效應質譜分析法（Evolved Gas Analysis-Mass Spectrometry，EGA-MS），得到不同受熱區間分佈圖的型態和各區間所佔重量百分比。當樣品量少時，則針對車漆內最常見的成分-聚苯乙烯加以定量，除了解聚苯乙烯在熱作用下的性質外，並考慮基質所帶來定量上的影響；最後再以上述方法分析能力測試樣品（Proficiency analytical test，PAT sample）以及實際樣品，並配合國內現行車禍肇事案件鑑定流程，評估在實務上的應用性。 本研究係針對現今車禍肇事案刑事鑑定，有突破之作法，在有限的證物下除可提供一般車漆成分比對外，更可以將分析資料數據化，而對於肇事逃逸案中肇事者責任之釐清與認定應有更進一步之助益。Qualitative analysis of complicated paint samples from traffic accident case could be usually dealt with by Fourier Transform Infrared Spectroscopy（FTIR）or Pyrolysis-Gas Chromatography/Mass Spectrometry（Pyrolysis-GC/MS）, however quantification of them were still difficult owing to many factors to be controlled , especially for solid and cured polymer. The study tried to design two quantification methods based on the amount of sample and operational pattern of instrument t. When the amount is adequate enough , we can get spectral patterns and relative mass ratio by thermogravimetry（TG）and evolved gas analysis（EGA）with temperature-program pyrolysis coupled with MS via a deactivated capillary metal tube. Polystyrene（PS）is the most commonly used component in paint recipes quantitated by Pyrolysis-GC/MS when the amount is limited . Not only the characteristics of PS during the continuous heating process are examined , but also discuss the matrix effects on quantification are discussed . We than access the applications on actual cases by joining round robin test and analyzing actual samples before fitting the method to civil operation-procedure finally. This study offers quantification technique by comparing data obtained from standard paints with those from the tiny paint chips on the limited sample for the actual forensic identification of traffic accident cases. With the developed method we can solve more suspected hit-and-run cases with good reliability.