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NCJRS Abstract

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NCJ Number: 164956 Find in a Library
Title: Update on the Use of the Sodium Rhodizonate Test for the Detection of Lead Originating From Firearm Discharges
Journal: Journal of Forensic Sciences  Volume:41  Issue:6  Dated:(November 1996)  Pages:1046-1051
Author(s): M R Bartsch; H J Kobus; K P Wainwright
Date Published: 1996
Page Count: 6
Type: Report (Technical)
Format: Article
Language: English
Country: United States of America
Annotation: The authors comprehensively investigated the chemistry associated with the Sodium Rhodizonate Test for particulate lead deposited on surfaces as a consequence of firearm discharges.
Abstract: The study explored some of the problems that have compromised the value of this test in forensic work, and the focus was on in vitro synthesis of colored lead complexes and the formation of these complexes on paper from gunshot residues. It was found that aqueous solutions of sodium rhodizonate were considerably more stable if stored below pH 3. The rhodizonate dianion was then diprotonated, forming rhodizonic acid, and the half-life of the solution increased from about 1 hour to about 10 hours. The formation of a nondiagnostic purple complex instead of the desired scarlet complex was avoided by ensuring the area to be examined was pretreated using tartrate buffer with a pH adjusted to 2.8 prior to treatment with rhodizonic acid. Whereas the scarlet complex changed to a blue-violet complex after secondary treatment which indicated the presence of lead, the purple complex decolorized completely under these conditions and its formation represented wastage of lead from within the test area. 7 references and 7 figures
Main Term(s): Science and Technology
Index Term(s): Criminal investigation; Criminalistics; Evidence identification; Firearms identification; Forensic sciences; Gunshot residue
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