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Video Densitometer

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Federal Forensic Associates, Inc.

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Carbon Paper Impressions The carbon copy document is one form of physical evidence that has not received much attention. Although the classical techniques employed to differentiate typewritten documents are often adequate to differentiate carbon copies, the following work suggests an additional technique. Thin Layer Chromatography has been used to differentiate many color containing mixtures, and its usefulness in differentiating carbon paper impressions is discussed.

Seven Common Explosive Materials High Pressure Liquid Chromatography (HPLC) can be used to analyze many types of forensic science evidence. Residue of explosives collected at the scene of an explosion is one of those types of evidence that is suited to HPLC analysis. HPLC was used to separate nitroglycerine (NG), ethyleneglycoldinitrate (EGDN), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX), pentacrythritoltetranitrate (PETN), 2, 4, 6, trinitrotoluene (TNT), and 2, 4, 6, trinitrophenylmethylmethylnitramine (tetryl).

Ball Pen Ink High pressure liquid chromatography (HPLC) was used to analyze several samples of ball pen ink. Analytical parameters were developed to analyze the various constituents of ball pen ink, both qualitatively and quantitatively. Different ball pen ink formulations were examined, as were batch samples of a single formulation.

Ball point pen The correlation between line characteristics and physical positioning of the pen is evaluated with the goal of determining the author of the writing. Line characteristics such as density, width and the presence of the anomalies, such as splitting and blobbing were noted and measured relative to writing angle and point load. Results suggest that the extreme variation which exists between writing instruments will prevent use of these techniques to determine authorship.

SACPF In crimes of fraud, paper evidence can have high evidentiary value. For example, paper analysis may detect numerous types of counterfeit documents such as currency, food stamps, stock certificates, wills and various types of identification documents such as drivers licenses or social security cards. In other situations the date of preparation of a document may be in question, and an exhaustive analysis of the paper may lead to a conclusion that the alleged date of preparation is not possible!

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