Contemporary Sci:Nonsci Majors

Contemporary Sci:Nonsci Majors - T o p ic s to C o v e r...

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1 Presumptive and Confirmatory Tests for Blood, Saliva, and Semen Topics to Cover Blood Enhancement Techniques Presumptive and confirmatory tests for blood Immunoassay techniques The detection of saliva The detection of semen • Blood, 8% total body weight, is comprised of two portions: – Plasma - fluid component: water (~91%), soluble proteins (~8%), organic acids (~1%), salts (~1%). – Formed elements (cellular material) • leukocytes (wbc), thrombocytes (platelets), • Erythrocytes, aka: red blood cells. – 4.8 - 5.4 million cells/mm 3 of blood – biconcave discs, made in the bone marrow – shed w/rest of cellular material during maturation THE NATURE OF BLOOD Heme • Heme is a ferroprotoporphyrin • Four coordination positions of the Iron aton are bound to the nitrogen atoms within the ring structure and one is bound to a histidine nitrogen in the globin protein. The remaining coordination is for O 2
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2 Once blood has been shed a series of hydrolytic and oxidation- reduction processes occur. Most tests for the indentification of blood rely on identification of heme or on the “peroxidase-like” activity of heme Heme Forensic Examination of Bloodstains Blood Enhancement – Crime Scenes & laboratory – Not specific/presumptive Presumptive tests – Easy, quick, sensitive. – Crime scenes & Laboratory – Can be subject to false positives Confirmatory tests – Not as sensitive as presumptive (typically) – Very specific – Generally completed in the lab – Immunological Blood Enhancement Techniques LUMINOL Used to enhance latent blood stains: blood is suspected but not seen
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This note was uploaded on 10/20/2010 for the course CHEM 004 taught by Professor Zysmilich during the Spring '06 term at GWU.

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Contemporary Sci:Nonsci Majors - T o p ic s to C o v e r...

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