L6_CHEM480_JCCYu - Crime Scene Chemistry Field Tests Test...

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1 Crime Scene Chemistry – Field Tests ± Test for the presence of blood ± Phenolphthalein (Kastle-Meyer) ± Leucomalachite green (LMG) ± Ortho-tolidine ± Luminol ± Tetra-methylbenzidine (TMB) ± Fluorescein ± Tests for the presence of body fluids ± Semen – acid phosphatase ± Saliva – amylase ± Urine – creatinine ± Fecal material – urobilinogen ± Gastric contents – gastric acid ± Tests for gun shot residues (GSR) and explosive ± Tests for controlled substances and drugs Test for the Presence of Blood ± Presumptive test for the presence of blood is to test the presence of heme, or heme-like derivative ± Heme: ± a principal component of hemoglobin ± Bearing ferrous ion ± False positive is possible with the presence of plant peroxidase or strong chemical oxidants. Heme (peroxidase) Oxidizable chemicals + hydrogen peroxide Æ oxidized (colorless) (colored) General Procedure of the Testing ± Swab a small amount of the suspect stain on a clean cotton swab moistened with saline. ± Swab a non-stained area from an adjacent area of the suspect stain, on the same surface as a control swab. ± Add two drops of the testing reagent, e.g. Kastle-Meyer reagent, onto each of the swabs. ± Wait 30 second. If a color transformation occurs at this point in the reaction. It is indicative of a false positive associated with the presence of a strong oxidizing agent or peroxidase acitivity ± Add two drops of hydrogen peroxide (3%) to each swab. ± Depending upon the particular testing reagent, a predictable colored complex will form within a brief period of time. Ranging from almost immediately to within 15 seconds.
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2 Test for the Presence of Blood ± Phenolphthalein (Kastle Phenolphthalein (Kastle-Meyer) Meyer) ± Sensitivity: 1:100,000
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L6_CHEM480_JCCYu - Crime Scene Chemistry Field Tests Test...

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