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Forensic methods material analysis

Established in 1894, AOAC International is an independent association of scientists and organizations in the public and private sectors devoted to promoting methods validation and quality measurements in the analytical sciences. AOAC has a mission to ensure the development, testing, validation, and publication of reliable chemical and biological methods of analysis for foods, drugs, feed-stuffs, fertilizers, pesticides, water, forensic materials and other substances affecting public health and safety and the environment. [Pg.267]

Using forensic photography as a precursor to any sample acquisition forms the foundation of the protocol, and allows purposive sampling. EDS should be performed to establish which elements to expect before attempting any quantitative elemental analysis such as ICP-OES/MS. Before working with actual artifacts, a set of replicated materials must be used and a successful trial run using the planned methods of analysis whether ICP-OES/MS, GC-MS or any others, must be achieved, so the methods of preparation can be adjusted properly. To facilitate this, appropriate materials must be replicated, which might mean that plants or minerals must be collected, and dyed or painted comparative standards must be created, so the unknown can be compared to the known. For many of the Old World dye plants these standards already exist. However, for North American dye plants comparative collections are in the early phases and subsequent analysis of colorant constituents have not yet been conducted (68,69). [Pg.38]

If the poison is not specified by name, the request to test for poisons is a major problem for the chemist, because there is no single chemical method of analysis capable of detecting all the various poisons. At least seven different analytical schemes are required to exclude even the most commonly encountered poisons (Fig. 1). Compared with toxicologists in academic research or industry, the task of the forensic toxicologist is made more difficult because the analytical material, the available time, and the resources are all severely limited. He has scarcely any control over the sampling time or the selection of material for analysis, and no certain knowledge that a poison is present. [Pg.36]

NAA is widely used in many different fields of sciences. Applications include environmental studies to characterize pollutants, semiconductor materials analysis to measure ultra trace-element impurities, archaeological studies of the distribution of the chemical elements and fossil materials, forensic studies as a non-destructive method (suspect chemical agents, see Figure 17.9), pharmaceutical materials analysis to measure ultra-trace element impurities, etc. Unfortunately, facilities for using this method do not exist everywhere. Otherwise, the sample becomes slightly radioactive, requiring the sample to be quarantined until its activity reaches a state similar to which it was before the NAA. [Pg.437]

Some early reports on investigations using NMR spectroscopy for forensic analysis were pessimistic about its application as a routine method. NMR was viewed as an insensitive technique when compared with some of the other methods of analysis the cost of the instrument was comparatively high and the results obtained required considerable expertise to interpret. This situation no longer exists. During the last several years, the amounts of material required... [Pg.3358]

In most cases, the analytical methods of the forensic chemist are different from those of the usual analytical, quality control, or materials chemists. The most important tests are usually those that lead to identification of the substances imder examination. Tests, such as those found in compilations of standard methods of analysis, are rarely of use in the criminalistics laboratory, because they generally require more sample than is available and are usually intended to measure some quantitative aspect of a material. For forensic purposes, initially, a qualitative identification is more important than a quantitative determination. Before the analyst can compare or attempt to individualize a trace sample, it is essential that it be identified. Comparisons performed on traces that have not been accurately identified represent a fault in principle and may come back to haimt the scientist during cross-examination. [Pg.3324]

Whilst for the analysis of plant material for cannabinoids both GC and HPLC are commonly used, in analytical procedures the employment of GC-based methods prevails for human forensic samples. Nonetheless, the usage of HPLC becomes more and more of interest in this field especially in combination with MS [115-120]. Besides the usage of deuterated samples as internal standards Fisher et al. [121] describe the use of a dibrominated THC-COOH (see 7.5). The usage of Thermospray-MS and electrochemical detection provide good performance and can replace the still-used conventional UV detector. Another advantage in the employment of HPLC rather than GC could be the integration of SPE cartridges, which are needed for sample preparation in the HPLC-system. [Pg.31]

Our personal civilian security is greatly enhanced by many contributions from chemistry and chemical engineering, often through integrated R D efforts with teams of scientists from many disciplines. Law enforcement employs forensic tools that rely heavily on chemical analysis, and emergency response teams use a variety of protective clothing and equipment that rely on modern materials chemistry and engineering. As mentioned above, individual security extends to chemical detection methods in the home. [Pg.173]

Microspectroscopy applies the identification power of infrared spectroscopy to the microscopic realm. Contaminants on printed circuit boards, blemishes in coatings, and other production defects can be isolated in situ and analyzed (see Electronics, coatings). Analysis of flaws that develop during use illuminates the method of failure. Microscopic samples, such as particulates filtered from air, can be analyzed individually. The forensic applications are many paint chips, single fibers, explosive residues, and inks on currency can all be identified nondestmctively (see Forensic chemistry). The structures of layered materials, such as laminated polymer films, are studied via microspectroscopy by cross-sectioning the materials and examining the individual layers edge on (47). [Pg.201]

Futhermore, difficulty is encountered with many specimens received for examination either because of the absence of accelerant or because of the type of material itself. Examples are (a) heavily charred wood, where all flammable accelerant has been lost, (b) a rag that was soaked in the water used by the fire department to extinguish the blaze, dried out, and forwarded to the forensic chemist for examination and (c) a sample of soap recovered near the site or origin. Analysis of the soap for an accelerant would exclude the solvent wash recovery method as well as any other method that might cause interference due to foaming. [Pg.112]

While as a general means of material study the method is universal in its capabilities, it is primarily in the analysis of polymers that it is useful for forensic purposes. The area where it is perhaps most needed and which also demonstrates the methodological approach best is that of fiber analysis. [Pg.115]


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