Forensic sciences materials examined

With these introductory comments in mind we would now like to examine the M.S. program in forensic chemistry that is being planned for September 1975 at Northeastern University. Personnel from the Institute visited many of the schools listed in Table I, as well as a number of practicing laboratories. We wish to thank all those who freely gave advice without their help we would not have been able to advance to the present stage. As in research, a team effort was made by members of the Institute in the curriculum development. Personnel experienced in forensic science interacted with chemists, toxicologists and materials scientists to achieve a final program. 

The issue of how a bulk sample should be described, sampled and analysed is equally problematic. The description itself is straightforward and should include all of the details relevant to a forensic science examination, including, for example, packaging, labelling, and the size, colour, weight, form and smell of the material. Sampling is a more difficult area. For small amounts of material. 

Nevertheless, if such an approach is to be used, then all underpinning forensic science principles should also be followed. The packaging and the data contained thereon should be recorded in a careful manner. The packaging should be opened and the materials subjected to morphological examination. They should then be re-instated and signature-sealed as appropriate. 

Forensic science encompasses a number of different fields of science. In this book, we are explaining the theories associated with high performance liquid chromatography, the different forms that it may take, and its use in some forensic applications. In this chapter, we will examine applications of HPLC in drug analysis, toxicology, analysis of explosives, analysis of coloured materials, and environmental science. 

The types of samples that are submitted to the forensic science laboratory for examination for the presence of explosives can include samples collected from the scene of the incident, from suspects, and from any sites where explosives are suspected to have been manufactured or processed. These samples can include debris collected from the site of the incident, remains of a detonating device, and clothing and hand swabs from suspects. (Other samples may also be collected, such as raw material that could have been used in the manufacture of explosives or explosive devices.)... 

The chemical characterization of forensic evidence from a crime scene or the criminal has some different requirements from that of many other types of chemical analysis. High sensitivity is important because the quantity of material for examination is often limited to minute traces found at the scene. The material under scrutiny must be characterized as comprehensively as possible to ensure maximum discrimination from other material in the same class. Forensic laboratories are multiinstrument facilities required to deal with many types of evidence found at a crime scene therefore, the routine methods used should preferably employ relatively inexpensive instrumentation. In order to protect integrity, samples should be analyzed as received if possible and any workup minimized. The method should preferably not be labor intensive. Pyrolysis-gas chromatography (Py-GC) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) have proven to be an effective means of satisfying these requirements in many forensic science laboratories. - ... 

The feasibility of using activation analysis to establish individuality characteristics resulted from studies made by Forshufvud, Smith and Wassen (280,281,876) and Smith (873) on the arsenic content of Napoleon I s hair and their interpretation of the arsenic content of the hair with respect to Napoleon s illness during 1816-1821. Since that time many other researchers have examined human hair, nails and other materials in order to assist in the identification of individuals in requirements of forensic science. Table V lists these investigators, the type of sample examined and the elements considered usable to determine individual characteristics. 

Scientific Working Group on Materials Analysis (SWG-MAT) (2002) Standard guide for using scanning electron microscopy/X-ray spectrometry in forensic paint examinations. Forensic Science Communications, U.S. Department of Justice, FBI, October 2002 vol. 4(4). Online http //www.fbi.gOv/hq/lab/fsc/backissu/oct2002/bottr-ell.htm. 

In the forensic science field, the examination of questioned documents is one of the most commonly carried out tasks. Its primary aims are to provide information about the material (to describe the different materials used and identify their origin) and the history of a document (the presence of traces of erased or modified entries in order to arrive at the truth regarding their integrity). 

Andrasko, J. "Microreflectance PTIR Techniques Applied to Materials Encoxmtered in Forensic Examination of Documents." Journal cf Forensic Sciences 41 (1996), 812-823. 

Among the various responsibilities of the forensic science laboratory is the examination of physical evidence from the scenes of suspicious fires. Physical evidence at the scene of a suspicious fire may be placed in either of two broad categories (1) residual materials of the type responsible for the initiation and acceleration of the fire and (2) physical evidence that may be primarily associated with one or more suspects in an incendiary fire (155). Examples of the latter are hair, paint, glass, blood, and fingerprints. With the exception of paint, GC is normally not utilized to analyze these latter examples, however GC has universally been the method of choice for analysis of ignitable liquid residues from fire debris. 

Beyond paints, fibers, and other polymers, PGC has been applied in the forensic science laboratory to characterize and compare a number of different types of material submitted as evidence in criminal casework. The utility of PGC for the characterization of adhesives has been described (253,272), as well as various methods for the comparison of tapes with adhesive backings (273). Vinyl tile with an asphalt-type glue from a safe-cracking case was analyzed by PGC (274). Williams and Munson (275) used capillary column PGC to examine 30 black... 

Forensic science Modern Raman spectrometers connected to microscopes enable the examination of small amounts of material such as single fibres. The sensitivity and selectivity of SERRS can be exploited in forensic science by determining the nature of the dye mixture in situ from a single fibre, from an ink or from a lipstick smear. 

Chromatography is a technique for separating and quantifying the constituents of a mixture. Separation techniques are essential for the characterization of the mixtures that result from most chemical processes. Chromatographic analysis is used in many areas of science and engineering in environmental studies, in the analysis of art objects, in industrial quahty control (qv), in analysis of biological materials, and in forensics (see Biopolymers, analytical TECHNIQUES FiNE ART EXAMINATION AND CONSERVATION FoRENSic CHEMISTRY). Most chemical laboratories employ one or more chromatographs for routine analysis (1). 

The cellulose fibers in paper are the starting material for regenerated fibers such as rayon and cellulose acetate, which, together, form the historical bridge from biopolymers to completely synthetic fibers. Synthetic rubber was created in Germany in 1917, but from the forensic perspective, a much more important advance was the S5mthesis of nylon (specifically, nylon 6,6) in 1935. The discovery of nylon is credited to Dr. Wallace Carothers, who worked at DuPont Chemical Corp. Initially, his work had been with esters and phenols, but he became interest in amides for possible use in the then-infant world of polymer science. What would become known as nylon was developed in 1935 and commercialized in 1939, initially for women s hosiery. World War n jump-started the polymer indu.stry, and many advances quickly followed. The emphasis here will be on fibers, with later sections in the chapter examining other applications of synthetic polymers. 

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