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Thin – Layer Chromatography

Chemistry 101 Laboratory. Thin – Layer Chromatography. Determining the components in “proprietary aspirins ”. Place 5 – 6 mLs of TLC solvent into a 100 – 150 mL beaker. Cover the beaker with a watch glass. Heat a melting point capillary over a very small flame.

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Thin – Layer Chromatography

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  1. Chemistry101 Laboratory Thin – Layer Chromatography Determining the components in “proprietary aspirins”

  2. Place 5 – 6 mLs of TLC solvent into a 100 – 150 mL beaker. Cover the beaker with a watch glass.

  3. Heat a melting point capillary over a very small flame. Rotate the capillary evenly with BOTH hands until the center softens (count about 5 seconds) and begins to sag; but DON’T PULL!!

  4. Remove the capillary from the flame and NOWpull . . . Hold it for a few seconds until the glass cools and re-sets.

  5. Snap the capillary in two at the center. Now you have TWO “spotters” .

  6. Draw a light origin line on the TLC plate JUSTABOVE the solvent level in the beaker; Place four evenly spaced dots on the origin line, and identify the proposed spots at the top of the plate.

  7. Place samples of the unknown and 3 references into spotting plates Dip a “spotter” into a sample; a bit of liquid is drawn into the capillary.

  8. Touch the “spotter” to the plate; a bit of sample will wet the dot. Blow on the spot to hasten drying. Repeat with other “spotters” at their respective dots.

  9. Place the plate into the beaker. It may take 10 – 15 minutes for the solvent front to approach the top. Mark the solvent front with a pencil, and allow the plate to air-dry.

  10. When is it dry, examine your plate in the UV light box: The components will appear as purple spots on greenish background; but will not be visible once the lamp is turned off.

  11. With a sharp pencil, circle the spots while under the light. Identify the components by comparing their positions with the references.

  12. Show your results to your instructor. If the results are not satisfactory, it will only take a few minutes to repeat the procedure.

  13. Sketch the results on your lab report. Identify the components you found.

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