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

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