chemical analysis part 1: qualitative analysis. chemical analysis one of the most important aspects...
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Chemical AnalysisPART 1: QUALITATIVE ANALYSIS
Chemical Analysis
One of the most important aspects of forensic science
Widely used in forensic analysisDevelop latent fingerprintObtain DNA Analyze unknown substanceIdentify drugs
Drug Identification
Use screening test first:Thin-layer chromatographyColor testMicrocrystalline test
Then instrumental analysis:SpectrophotometryMass spectrometryGas chromatography
Chromatography
The physical separation of a mixture into its individual components
Analyzing multi-component samplesInks, dyes, drugs, and poisons, etc.
Examples of Chromatography
Liquid Chromatography
Thin-Layer Chromatography(TLC)
Gas Chromatography
Paper Chromatography
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
Detect the colorless components separated from TLC
• Exposing to UV light• Exposing to fluorescent dyes• Exposing to iodine• Spraying with a reagent
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
Paper & Thin-layer Chromatography Tutorial
https://www.youtube.com/watch?v=J8r8hN05xXk
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
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