Forensic materials

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. 

Nielsen K, Kaempe B, Jensen-Holm J Fatal poisoning in man by 2,4-diphenoxyacetic acid (2,4-D) Determination of the agent in forensic materials. Acta Pharmacol Toxicol 22 224-234, 1965... 

Ceo RN, Kazerouni MR, Rengan K. 1993. Chelex 100 as a Medium for Simple Extraction of DNA for PCR-based T3rping from Forensic Material. Biotechnique 1993 10 506-513. 

Most biomedical, forensic, materials and industrial applications of chemical imaging require ... 

The coincidence technique has also been applied to the activation analysis of biological materials 79 82) and forensic materials 83>. 

Standard reference collections. The Law Enforcement Standards Laboratory of NBS has been investigating the needs and uses of standard reference files or collections of select groups of forensic materials. 

A tentative data base has been established based upon surveys and interviews with criminalists, educators, scientists and manufacturers. Existing forensic material collections and data files have been located and evaluated. New proposed forensic material collection specifications have been developed including recommendations relating to size, scope and costs of development. The report, although not yet published,... 

Recent work has shown that materials science can make a substantial and growing contribution to criminalistics. As a result, forensic materials science may become a field of its own in the future. 

In this context we note that the curriculum for the planned M.S. program in Forensic Chemistry at Northeastern University which is discussed in detail in Reference 2 will contain a new course entitled "Forensic Materials" as a step in the direction indicated above. The abstract of this course is as follows Forensic Materials (2 Quarter Hours) Fundamental types of solids, such as metals, ceramics, minerals, organic solids, including drugs, polymers, plastics, fibers their properties and determination by modern methods. Forensically important materials such as alloys, glass, soils, fibers, wood, paper, rubber, dyes, paints, ink, and their determination. Illustration of various materials as associative or dissociative items of evidence. 

Typical Areas of Forensic Materials Science. In the following, some types of forensic materials and tasks involving them which arise in a crime laboratory are listed, and possible applications of the materials scientific approach to these substances and tasks are briefly described. 

The list of new methods given above is incomplete and is intended only as a guide to the techniques that the forensic materials scientist may introduce into the field. For most of the materials properties we have considered here the establishment of reference libraries listing characteristic values and their variation through the population would be necessary to make any... 

Paper is one of the more common evidential materials encountered in crimes such as forgery, conspiracy, threatening letters and kidnapping its examination is therefore frequently required in the forensic laboratory (21). (Another aspect of document examination, viz., ink analysis, is treated in another chapter of this volume (22).) As with other forensic materials, two questions commonly arise ... 

Heretofore, Raman spectroscopy has not played a role in forensic science because of the fluorescent problems and the sample alignment, which is time-consuming. As a consequence, the technique was never seriously considered as a routine tool to study forensic materials. However, with the development of FT-Raman spectroscopy, the technique is now being reexamined. One such application in forensic science follows (15). 

Fibers are another important source of forensic material. Both synthetic and natural fibers were analyzed by pyrolysis, the pyrograms or Py-MS data generating a fingerprint that can be diagnostic for each type of fiber [13]. 

A recent innovation in electron microscopy is environmental SEM, which allows samples to be studied at pressures and humidities that approach ambient conditions. To achieve this, several stages of differential pumping between the electron gun and the sample are used, and the sample itself is placed in a vacuum of a few hundred Pascals. Environmental SEM enables many materials to be examined without pretreatment, unlike conventional SEM, in which specimens must be solid, dry and usually electrically conductive. This now makes possible studies of the natural, unadulterated surfaces of specimens such as polymers, biological tissues and cells, food and drugs and forensic materials. 

This book is intended to be a practical guide to the application of pyrolysis techniques to various samples and sample types. To that end, general and theoretical considerations, including instrumentation and degradation mechanisms, have been consolidated in the first two chapters. The balance of the book describes the use of pyrolysis as a tool in specific fields. Synthetic polymers, forensic materials, and other samples with a long history of analysis by pyrolysis are covered. In addition, we have been pleased to see some new areas of study, such as the analysis of surfactants, antiquities, and environmental materials, and these topics are presented as well. 

No single method can be recommended for handling special samples. These might include special research preparations, archeological samples, forensic materials, and other nonroutine substances. The size of the sample available, the desired data, and the value of the sample all affect the selection of analytical procedures. A qualitative analysis, obtained by totally vaporizing the sample, can often provide much useful information concerning major and minor constituents of the sample and the photographic plate provides a permanent record of the sample composition. 

The importance of paints as physical evidence has been recognized for quite some time. In fact, paints are among those forensic materials that have engaged the attention of crime investigators and concerned scientists since the inception of forensic science laboratories, and they have always played important and crucial roles in crime investigation. 

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