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BASED ON POLARITY

BASED ON POLARITY. Paper Chromatography. https://www.youtube.com/watch?v=ej2zXOwASVI. What is Chromatography?. Chromatography is a technique for separating mixtures into their components. Identify. Separate. Mixture. Components. Uses for Chromatography.

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BASED ON POLARITY

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  1. BASED ON POLARITY

  2. Paper Chromatography https://www.youtube.com/watch?v=ej2zXOwASVI

  3. What is Chromatography? Chromatography is a technique for separating mixtures into their components Identify Separate Mixture Components

  4. Uses for Chromatography Real-life examples of uses for chromatography: • Hospital – detect alcohol/drug levels in blood • Police – to compare a sample at a crime scene to a suspect sample • Environmental Agency –find pollutants in the water supply

  5. Definition of Chromatography Detailed Definition: Chromatography separates components (parts) within a mixture by using the differential affinities of the components for the mobile medium and for the stationary medium (absorbing) Terminology: Differential– difference Affinity – attraction (polar or nonpolar) Mobile Medium – the moving part (solvent, like water or alcohol). The liquid (or gas) that carries the mixture. Stationary Medium – the part that does not move (the paper or gel) What is important is how much they adsorb on the stationary phase versus how much they dissolve in the mobile phase

  6. TLC AND PAPER https://www.youtube.com/watch?v=J8r8hN05xXk

  7. Capillary Action–the movement of liquid within the spaces of a porous material. The paper’s plant cells themselves are made of cellulose and are which is polar have water in them and between them which is polar. Due to electric forces he liquid is able to move up the filter paper because the attractions is stronger than the force of gravity. Separation of components depends on both their solubility in the mobile phase and their affinity to the stationary phase. Principles of Paper Chromatography

  8. Thin Layer Chromatography (TLC)

  9. Illustration of Chromatography Stationary Phase Separation Mobile Phase Mixture Components

  10. Visualizing Agents The sample (analyte) when it separates may not be visible, so a dye is used (already impregnated on the TLC gel) or UV light. Ex ninhydrin purple

  11. Rf = distance moved by substance distance solvent front Substances that are soluble in the liquid the Rf will be close to .... 1, as it heads to the top For substances that are rather insoluble in the liquid Rf will be close to .... 0, they don’t move Thus all numbers must never be more than 1 for Rf Notice Retardation factor (above) is based on distance for Paper and TLC. Next we visit HPLC and GLC which will not measure Distance, rater the measure retention time spent inside a column.

  12. Column Chromatography Adsorbents: Alumina & Silica gel (is porous sand) in which more polar molecules are adsorbed morestrongly & thus, will elute more slowly

  13. COLUMN CHROMATOGRAPHY Stationary phase silica Mobile phase suitable organic solvent Separation components interact with the stationary phase to different extents Method • a chromatography column is filled with solvent and silica • drops of the mixture (analyte) are placed on top of the silica - A • the tap is opened to allow the solvent to flow out • components travel through at different rates and separate - B • batches of solvent are collected at intervals - C • the solvent in each batch is evaporated to obtain components A B B C

  14. HIGH PRESSURE LIQUID CHROMATOGRAPHY (HPLC) A better form of column chromatography. Instead of draining down through the stationary phase, the solvent is forced through under high pressure. Stationary phase silica (tiny solid micro beads) Mobile phase suitable solvent Separation similar to column chromatography Alumina is also used (Al2O3) with Iron impurities you get a sapphire And chromium impurities = ruby

  15. HPLC Column Detector Injector Column Mixture of compounds A B C D Made by RW

  16. Detector Injector Column C A B D

  17. Detector C A B D Injector Column Different substances stick to the column and pass through at different speeds. Amount The detector makes a graph Time

  18. Each peak is a chemical in the mixture. C eluted first. D B B C A

  19. HLPC https://www.youtube.com/watch?v=a2wwgLV80U8

  20. GAS LIQUID CHROMATOGRAPHY (GLC) Stationary phase liquid adsorbed on an inert solid support Mobile phase gas Method a sample is injected and vaporized then carried along by an inert gas column contains a liquid stationary phase, adsorbed onto an inert solid the time taken to travel through the tube will depend on how much time is spent moving with the gas rather than being attached to the liquid.

  21. GAS LIQUID CHROMATOGRAPHY (GLC) Detection one method is an FID - flame ionisation detector The FID • as a component exits, it is burned in a hydrogen flame • ions are produced • detected as the ions produce an electric current • the greater the amount = larger current • the current can be represented by a chromatogram

  22. GLC https://www.youtube.com/watch?v=08YWhLTjlfo

  23. What happens in practice. • Compounds that have high affinity for mobile phaseemerge first, (most volatile). • Chromatogram charts recorder response against time. • Retention time – characteristic of the compound under given conditions.

  24. GAS LIQUID CHROMATOGRAPHY (GLC) Interpretation • the areas under the peaks are proportional to the amount of a compound • retention times are used to identify compounds – they are found out by putting known compounds through the system under similar conditions and comparing the knowns to the sample. If they match we have identified the chemical The area under a peak is proportional to the amount present. Each component has a different retention time.

  25. Summary4 Types of Chromatography

  26. Interesting$1 Centrifuge https://www.youtube.com/watch?v=L5ppD07DMKQ

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