Part 1: qualitative analysis Chemical Analysis Part 1: qualitative analysis
Chemical Analysis One of the most important aspects of forensic science Widely used in forensic analysis Develop latent fingerprint Obtain DNA Analyze unknown substance Identify drugs
Drug Identification Then instrumental analysis: Use screening test first: Thin-layer chromatography Color test Microcrystalline test Then instrumental analysis: Spectrophotometry Mass spectrometry Gas chromatography
Chromatography The physical separation of a mixture into its individual components Analyzing multi-component samples Inks, dyes, drugs, and poisons, etc.
Examples of Chromatography Liquid Chromatography Thin-Layer Chromatography (TLC) Gas Chromatography Paper Chromatography
Thin-Layer Chromatography TLC Use a solid stationary phase and a moving liquid (mobile)phase to cause a separation of the components of a mixture Solvent Front Heroin Quinine Origin
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) value Solvent finish 10 cm Rf (retention factor) value 8 cm The 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 Rf1 = 8/10 = 0.8 4 cm Rf2 = 4/10 = 0.4 Starting point
Paper & Thin-layer Chromatography Tutorial https://www.youtube.com/watch?v=J8r8h N05xXk
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