Ch 5 - Organic Analysis

1. Ch 5 - Organic Analysis • Elements and compounds. • Solids, liquids, and gases. • Phase • Organic vs inorganic compounds. • Qualitative vs quantitative analysis. • Henry’s law and equilibrium state. • Chromatography. • Retention time.

2. Thin-layer vs gas chromatography. • Rf value. • Electrophoresis. • Theories of light: wave vs particle. • Electromagnetic spectrum. • Relationship between color and absorption of light by molecules. • Beer’s law. • Absorption spectrophotometer. • Ultraviolet (UV) and Infrared (IR) spectrum for identification of organic compounds.

3. Mass Spectrometry (MS) • Significance of mass spectrum in forensic science.

4. Matter: all things of substance. Matter is composed of atoms or molecules. • Element: a fundamental particle of matter. An element cannot be broken down into simpler substances by chemical means. • Periodic table: chart of elements arranged in a systematic fashion. Vertical rows are called groups or families; horizontal rows are called series. Elements in a given row have similar properties. • Compound: a pure substance composed of two or more elements

5. Physical state: a condition or stage in the physical being of matter; a solid, liquid, or gas • Solid: a state of matter in which the molecules are held closely together in a rigid state • Liquid: a state of matter in which molecules are in contact with one another but are not rigidly held in place • Gas (Vapor): a state of matter in which the attractive forces between molecules are small enough to permit them to move with complete freedom • Sublimation: a physical change from the solid directly into the gaseous state

6. Phase: a uniform piece of matter; different phases are separated by definite visible boundaries • Organic: a substance composed of carbon and hydrogen, and, often, smaller amounts of oxygen, nitrogen, chlorine, phosphorus, or other elements • Inorganic: a chemical compound not based on carbon • Spectrophotometry: an analytical method for identifying a substance by its selective absorption of different wavelengths of light

7. Chromatography: any of several analytical techniques whereby organic mixtures are separated into their components by their attraction to a stationary phase while being propelled by a moving phase • Pyrolysis: the decomposition of organic matter by heat • Fluoresce: to emit visible light when exposed to light of a shorter wavelength-i.e., ultraviolet light

8. Electrophoresis: a technique for the separation of molecules through their migration on a support medium while under the influence of an electrical potential • Proteins: polymers of amino acids that play basic roles in the structures and functions of living things • Enzyme: a type of protein that acts as a catalyst for certain specific reactions • Visible light: colored light ranging from red to violet in the electromagnetic spectrum

9. Wavelength: the distance between crests of adjacent waves • Frequency: the number of waves that pass a given point per second • Electromagnetic spectrum: the entire range of radiation energy from the most energetic cosmic rays to the least energetic radio waves • X-ray: a high energy, short wavelength form of electromagnetic radiation

10. Laser: light amplification by the simulated emission of radiation. Light that has all its waves pulsating in unison • Photon: a small pocket of electromagnetic radiation energy. Each photon contains a unit of energy equal to the product of Planck’s constant and the frequency of radiation: E= hf • Monochromator: a device for isolating individual wavelengths or frequencies of light • Monochromatic light: light having a single wavelength or frequency

11. Ultraviolet: Invisible long frequencies of light beyond violet in the visible spectrum • Infrared: invisible short frequencies of light before red in the visible spectrum • Ion: an atom or molecule bearing a positive or negative charge

12. Gas Chromatograph (GC)

13. Thin-Layer Chromatography (TLC)

14. Electrophoresis

15. Electromagnetic Spectrum

17. UV-VIS Spectrophotometer

18. UV-VIS Spectrum

19. IR Spectrophotometer

20. IR Spectrum

21. Mass Spectrometer (MS)

22. Mass Spectrometer

23. Mass Spectrum

24. Ch.5 Organic Analysis Chromatography

28. Chromatography Separation of Mixtures

29. What Is Chromatography? • A family of laboratory techniques for separating mixtures into their component compounds • Uses some version of a technique in which two phases, one mobile, one stationary, flow past one another • The mixture separates as it interacts with the two phases

30. Basic Principle • Different compounds will stick to a solid surface with different degrees of strength or vary in the efficiency with which they dissolve in a liquid

32. Basic Principles • A mobile phase sweeps the sample over a stationary phase • like the wind sweeps the swarm over the flower bed

33. Basic Principles • When a mixture of compounds flows over a surface, the molecules will stick to the surface • If a molecule does not stick to the surface too strongly, the molecule stick & unstick many times as it is swept along the surface • Over time, the molecules will become physically separated from each other

35. Basic Principles • When the molecules reach the far end of the surface, they are detected or measured one at a time as they emerge • Chromatography is non-destructive • does not alter the molecular structure of the compounds

38. Types of Chromatographic Attraction • Adsorption Chromatography • depends on physical forces such as dipole attraction to cause the molecules to “stick” to the stationary phase • column, TLC, HPLC

39. Types of Chromatographic Attraction • Partition Chromatography • depends on the relative solubility of the mixture’s molecules in the stationary phase coating • polarity may also have some effect • gas chromatography

40. Types of Chromatographic Attraction • Size-exclusion • the relative sizes of the molecules determine how fast the molecules move through the stationary phase • large molecules flow right through • small molecules spend time trapped in the pores of the stationary phase • gel filtration chromatography

41. Types of Chromatographic Attraction • Ion-exchange • depends on the relative strength with which ions interact with an ionic resin • less strongly held ions are displaced by more strongly attaching ions • one kind of ion is exchanged for another • ion exchange chromatography

42. Paper Chromatography • Stationary phase • a sheet or strip of paper • mobile phase • a liquid solvent • Sample mixture spotted onto the paper • Capillary action moves mobile phase through stationary phase

43. Paper Chromatography • Components appear as separate spots spread out on the paper after drying • Can be used for ink analysis

44. Paper Chromatography • 2D Chromatography • accomplished by running another chromatography with the paper turned 90o • Can complete separation of overlapping compounds

45. Thin Layer Chromatography • Stationary Phase • a thin layer of adsorbent coating on a sheet of plastic or glass • usually Al2O3 (alumina) or SiO2 (silica) • Mobile Phase • a liquid solvent • Sample mixture spotted onto the adsorbent

46. TLC • Some components bind to the adsorbent strongly; some weakly • Components appear as separate spots after development

47. Retention Factor (Rf) • quantitative indication of how far a compound travels in a particular solvent • good indicator of whether an unknown & a known compound are similar, if not identical • If the Rf value for the unknown compound is close to or the same as that for the known compound, the two compounds are most likely similar or identical

48. Retention Factor (Rf) • Rf = distance the solute (D1) moves divided by the distance traveled by the solvent front (D2) • Rf = D1 / D2 • Rf <1.0

49. Gas Chromatography • Stationary phase • a solid or very syrupy liquid lines a tube (column) • silicone polymers (like Silly Putty) commonly used • Mobile phase • an inert gas • nitrogen • helium