How to Test an Organic Compound for Purity

Written by soumy ana
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How to Test an Organic Compound for Purity
To test an organic compound for purity, you need to determine its melting point. (Creatas Images/Creatas/Getty Images)

Organic compounds are natural products that contain carbon and hydrogen. They include carbohydrates (sugar, plants), proteins (fats, waxes, steroids), lipids and nucleic acids. You will often find organic compounds in the form of mixtures, so you must assess their purity before using them. Too many impurities can lead to explosions or fires. Impurities in medical substances can injure or kill a patient.

One of the easiest ways to test an organic compound for purity is to find the melting point of a similar pure substance, then warm your sample and compare the melting points of both substances.

Skill level:

Things you need

  • Mortar and pestle
  • Glass capillary tube
  • Pan
  • Platinum resistance thermometer or heat resistant thermometer

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  1. 1

    Obtain a table of organic compounds' melting points. Clean a glass capillary tube with a neutral detergent. Dry it. Use a mortar and pestle to reduce your sample to powder.

  2. 2

    Put the powder inside the capillary tube. Pack the powder homogeneously. Put a high-accuracy thermometer that sustains heat inside the pan.

  3. 3

    Put the tube in a pan full of warm water. Heat the water to a few degrees below the expected melting point.

  4. 4

    Look at your sample carefully and record the temperature on the thermometer when you see the sample melting.

Tips and warnings

  • The traditional method relies on visual detection; however, you can also buy an OptiMelt for more scientific precision.
  • Fill the tube to a maximum of 3.0mm.
  • Clean your tube and dry it completely before use.
  • If your sample turns into gas at high temperatures, seal your tube.

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