chemical analysis part 1: qualitative analysis. chemical analysis one of the most important aspects...
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Chemical AnalysisPART 1: QUALITATIVE ANALYSIS
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Chemical Analysis
One of the most important aspects of forensic science
Widely used in forensic analysisDevelop latent fingerprintObtain DNA Analyze unknown substanceIdentify drugs
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Drug Identification
Use screening test first:Thin-layer chromatographyColor testMicrocrystalline test
Then instrumental analysis:SpectrophotometryMass spectrometryGas chromatography
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Chromatography
The physical separation of a mixture into its individual components
Analyzing multi-component samplesInks, dyes, drugs, and poisons, etc.
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Examples of Chromatography
Liquid Chromatography
Thin-Layer Chromatography(TLC)
Gas Chromatography
Paper Chromatography
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Thin-Layer Chromatography TLC
Solvent Front
Heroin
Quinine
Origin
Use a solid stationary phase and a moving liquid (mobile)phase to cause a separation of the components of a mixture
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Detect the colorless components separated from TLC
• Exposing to UV light• Exposing to fluorescent dyes• Exposing to iodine• Spraying with a reagent
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Rf (retention factor) valueThe distance traveled
by the component divided by the distance traveled by the solvent
It is usually expressed as a decimal
Identify components by comparing to known chemicals
Solvent finish 10 cm
8 cm
4 cm
Starting point
Rf1 = 8/10 = 0.8
Rf2 = 4/10 = 0.4
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Paper & Thin-layer Chromatography Tutorial
https://www.youtube.com/watch?v=J8r8hN05xXk
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Color Test
Initial screening for drugs
Color changes when certain chemicals present
Very simple and less expensive
http://www.aetv.com/crime-360/video/drug-reagent-test
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Microcrystalline Test
More specific than color test
Specific chemical will form specific size and shape of crystal
Quick, cheap, and no isolation required Copper Sulfate X 100