5-1 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein Chromatography –means of separating and tentatively identifying the components of a mixture.

5-2 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein Chromatography Molecules that have a preference for the moving phase will slowly pull ahead and separate from those substances that prefer to remain in the stationary phase.

5-3 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein An analogy

5-4 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein Paper Chromatography

5-5 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein Rf Values

5-6 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein Calculate the Rf value for each spot

5-7 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein TLC TLC uses a solid stationary phase usually coated onto a glass plate and a mobile liquid phase to separate the components of the mixture.

5-8 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein TLC The liquid will slowly rise up the plate by capillary action –the sample to become distributed between the stationary phase and the moving liquid phase. Most compounds are colorless –materials must be visualized by placing the plates under ultraviolet light or spraying the plate with a chemical reagent. R f values calculated.

5-9 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein Gas Chromatography Research gas chromatography. Create a brochure individually that answers the following questions. –What is gas chromatography (GC)? –How does GC work? (Find a visual to help illustrate this) Describe using a few sentences. –What does a gas chromatograph set up look like? What are the parts? Find or draw a visual and label! –What is the written record or data from a GC look like? What is it called? Find an example and print it. –Why/how is GC used in Forensic Science?