1 / 15

Chromatography

Chromatography. Chem 2411L Dr. Clower. Chromatography. Separation of components of a mixture Stationary phase Solid Liquid coated on solid Mobile phase (flow over stationary phase) Liquid Vapor Components distribute over phases based on affinity for either phase.

nariko
Download Presentation

Chromatography

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chromatography Chem 2411L Dr. Clower

  2. Chromatography • Separation of components of a mixture • Stationary phase • Solid • Liquid coated on solid • Mobile phase (flow over stationary phase) • Liquid • Vapor • Components distribute over phases based on affinity for either phase

  3. Types of Chromatography • Column Chromatography • Thin Layer Chromatography (TLC) • Paper Chromatography • Gas Chromatography (GC) • Mass Spectrometry (MS) • High Performance Liquid Chromatography (HPLC)

  4. Column Chromatography • Vertical glass column • Mobile phase = liquid • Pure solvent or mixture of solvents • Typically nonpolar → polar • Stationary phase = solid • Silica gel (SiO2) • Alumina • Sample = Solid or liquid placed on column

  5. Column Chromatography, cont. • Affinity = molecules adsorbed on solid • Compound in liquid elute first • More polar molecules elute last • Size • Collect separated compounds (fractions) • Evaporate solvent • ID or further purify

  6. Thin Layer Chromatography • Similar to column chromatography • Mobile phase = solvent • Chosen for polarity • Often mixtures • Trial and error • Stationary phase = solid (silica gel) • plastic or glass backing • Sample = spot on plate (1-2 mm) • Dissolve sample in volatile solvent • Drop with tiny capillary

  7. TLC, cont. • Solvent chamber • TLC Plate • Detect spots • UV lamp • Fluorescent dye in adsorbent layer • I2 vapor • Rf = distance spot moved / distance solvent moved • Compare Rf value to known sample on same plate

  8. Usefulness of TLC • To determine the # components of a mixture • To test fractions from column chromatography • To choose a solvent for column chromatography • To monitor a reaction • Does NOT tell you how much of each component is in a mixture

  9. Paper Chromatography • Similar to TLC • Stationary phase = H2O adsorbed by cellulose • Mobile phase = solvent • Frequently used for polar compounds • Amino acids, carbohydrates, etc.

  10. Gas Chromatography • Mobile phase = stream of inert gas • Stationary phase = high boiling liquid film • Polarity similar to compounds in mixture • Polymers • Supported on a solid • Packed in a column • Heated glass or metal • 2-3 m in length; 2-5 mm diameter • Sample = injection from syringe (1 mL) • Often add 1 mL air

  11. GC, cont. • Affinity = vapor vs. liquid • Separated components • Pass by detector • Send signal to electronic recorder • Can be collected for further analysis (rare) • Signal display = peaks • Area under peak = % of mixture • ½ b x h • Integrated • Massed on balance • Analysis • Retention time (min.), Area, % of mixture

  12. Gas Chromatogram • Retention time can be used to ID a component if compared to known sample under same conditions • Flow rate, column size, temperature, etc.

  13. MassSpectrometry • Used with GC • Break molecules into ions (fragments) M → M•+ + e- M•+→ A+ + X A+→ B+ + Y etc. • Gives mass of molecular ions, fragment ions • Plot relative abundance vs. mass to charge ratio

  14. Methyl Benzoate

More Related