Experimental Procedures for Quantitative Analysis of Fats

1. Determination of Saponification Value

A. Preparation of Test Sample

  1. Accurately weigh 1 g of oil and transfer it into a clean beaker.
  2. Pour the oil from the beaker into a conical flask.
  3. Add 5 mL of ethanol to the flask.
  4. Shake the mixture thoroughly to dissolve the oil.
  5. Add 25 mL of potassium hydroxide (KOH) solution to the flask.
  6. Shake the mixture again to ensure complete mixing.

B. Preparation of Blank Sample

  1. Add 10 mL of ethanol into a separate flask.
  2. Add 25 mL of KOH solution to the same flask.
  3. Shake the blank sample thoroughly.

C. Refluxing

  1. Attach a reflux condenser to both the test and blank flasks.
  2. Heat both samples in a boiling water bath for 1 hour.

D. Titration

  1. Add a few drops of phenolphthalein indicator to the test sample and shake.
  2. Similarly, add a few drops of phenolphthalein to the blank sample and shake.
  3. Titrate the test sample using a burette until the endpoint is reached.
  4. Record the burette reading for the test sample.
  5. Titrate the blank sample in the same manner.
  6. Record the burette reading for the blank sample.
  7. Use both readings to calculate the saponification value.

2. Determination of Acid Value

  1. Weigh 1 g of oil and transfer it to a beaker.
  2. Pour the oil into a conical flask.
  3. Add 20 mL of ethanol to the flask.
  4. Shake well to dissolve the oil completely.
  5. Add a few drops of phenolphthalein indicator.
  6. Shake the solution again.
  7. Titrate the mixture using a standard alkali solution until a faint permanent pink color appears.
  8. Record the burette reading.
  9. Use the recorded value to calculate the acid value of the oil.

3. Determination of Iodine Value

A. Preparation of Test Sample

  1. Weigh 3 g of oil and transfer it to an iodine flask.
  2. Add carbon tetrachloride to dissolve the oil.
  3. Shake the mixture thoroughly.
  4. Add iodine monochloride solution to the flask.
  5. Shake the mixture again for proper reaction.

B. Preparation of Blank Sample

  1. Add carbon tetrachloride into another iodine flask.
  2. Add iodine monochloride solution to the same flask.
  3. Shake the blank sample thoroughly.

C. Dark Incubation

  1. Place both the test and blank samples in a dark place for 30 minutes to allow complete reaction.

D. Titration

  1. Titrate the test sample using standard sodium thiosulfate solution.
  2. When the solution becomes light yellow, add starch indicator.
  3. Continue titration until the blue color disappears.
  4. Record the burette reading for the test sample.
  5. Repeat the same titration process for the blank sample.
  6. Record the burette reading for the blank sample.
  7. Use both values to calculate the iodine value.