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synopsisA method haa been developed for the determination of per cent ethylene incorporation in ethylene-propylene block copolymers by infrared spectroscopy. Standardization is done from mixtures of the homopolymers. Both standards and samplea are scanned at 180OC. in a spring-loaded demountable cell. The standardization waa confirmed by the analysis of copolymers of known ethylene content prepared with C14-labeled ethylene. By comparison of the infrared resuite from the analyses performed at 18oOC. and also at mom temperature, the p m n c e of ethylene homopolymer can be detected. An equation haa been derived for the quantitative estimation of per cent ethylene present as copolymer blocks.

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In 1975 personnel at the Institute of Forensic Sciences realized that a full range of analytical technics was not being used in the examination of evidence from suspicious fires. Simple steam distillation was followed by infrared spectroscopic examination, but in a distressing number of cases no apparent accelerant was detected. Midkiff and Washington [1] described the use of gas-liquid chromatography (GLC) with headspace sampling, and Cain [2] followed with capillary column GLC. Later Yip and Clair [3] developed a system for identifying trace amounts of petroleum produced from fire debris. As they pointed out, the most common accelerants encountered are naphtha (C5 to C8 hydrocarbons), gasoline (C5 to C12 hydrocarbons), and fuel oils (C8 to C22 hydrocarbons). From work described in these papers, modifications suitable to available instrumentation evolved.