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NCJ Number: 51786 Add to Shopping cart Find in a Library
Title: SCIENTIFIC STUDY OF PENCIL LEAD COMPONENTS
Journal: JOURNAL OF FORENSIC SCIENCES  Volume:23  Issue:4  Dated:(OCTOBER 1978)  Pages:643-661
Author(s): S CAIN; A A CANTU; R BRUNNELLE; A LYTER
Corporate Author: American Soc for Testing and Materials
Promotions Manager
United States of America

American Acad of Forensic Sciences
United States of America
Date Published: 1978
Page Count: 19
Sponsoring Agency: American Acad of Forensic Sciences
Colorado Springs, CO 80901-0669
American Soc for Testing and Materials
West Conhohocken, PA 19428-2959
US Dept of the Treasury
Washington, DC 20220
Sale Source: US Dept of the Treasury
1500 Pennsylvania Avenue, NW
Washington, DC 20220
United States of America
Type: Report (Study/Research)
Language: English
Country: United States of America
Annotation: THIN-LAYER CHROMATOGRAPHY (TLC) IS USED TO SEPARATE WAX PRODUCTS USED IN PENCILS AND TO INVESTIGATE THE EFFECTS OF CLAYS, RESINS, AND OTHER ORGANIC FILLERS AND BINDING AGENTS IN PAPER ON IDENTIFICATION OF PENCIL TYPES.
Abstract: THE PENCIL LEADS USED BY THE 17 MAJOR PENCIL MANUFACTURERS IN THE UNITED STATES WERE SUBJECTED TO A SERIES OF TESTS TO ANALYZE THEIR CHEMICAL AND PHYSICAL CHARACTERISTICS. THE PURPOSE WAS TO DETERMINE THE FEASIBILITY OF IDENTIFYING A SPECIFIC TYPE OF PENCIL AS THE INSTRUMENT USED IN A PIECE OF WRITING. FOLLOWING AN OVERVIEW OF THE PENCIL MANUFACTURING PROCESS, THE WAXES AND CLAYS USED TO BIND THE GRAPHITE IN A PENCIL LEAD ARE DESCRIBED. TLC WAS CHOSEN FOR THE ANALYSIS BECAUSE OF ITS ABILITY TO EFFECTIVELY DIFFERENTIATE WAX PRODUCTS USING ONLY MICROGRAM AMOUNTS OF SAMPLE. THE EXPERIMENTAL TECHNIQUE USED IS DESCRIBED IN DETAIL. TYPICAL X-RAY SPECTRUMS OBTAINED BY THE ANALYSES ARE ILLUSTRATED. THE INTERACTION OF VARIOUS FILLERS AND COATINGS IN PAPER ON THESE SPECTRUMS WAS ALSO EXAMINED. IT WAS FOUND THAT THE TLC TECHNIQUE SUCCESSFULLY DIFFERENTIATED VARIOUS MANUFACTURERS' PENCIL LEADS AND THAT THE PROCEDURE WAS BOTH PRACTICAL AND RELIABLE. HOWEVER, IT WAS IMPOSSIBLE TO LIFT SUFFICIENT LEAD FROM A SAMPLE OF WRITING ON PAPER TO PERMIT IDENTIFICATION. THE CONTAMINATING PAPER COMPONENTS SERIOUSLY INTERFERED WITH THE TLC IDENTIFICATION. IT IS SUGGESTED THAT MORE SENSITIVE TECHNIQUES, SUCH AS LIQUID CHROMATOGRAPHY, GAS-LIQUID CHROMATOGRAPHY, OR OTHER MICROSCOPY TECHNIQUES, BE INVESTIGATED FOR THIS PURPOSE. THE POSSIBILITY OF USING TRACE ELEMENTS TO DIFFERENTIATE AMONG WRITING SPECIMENS ON PAPER IS BRIEFLY DISCUSSED. SUPPORTING DATA AND REFERENCES ARE PROVIDED. (GLR)
Index Term(s): Chromatography; Crime laboratories; Document analysis; Evidence identification; Studies; Techniques; Trace evidence
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http://www.ncjrs.gov/App/publications/abstract.aspx?ID=51786

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