analisa kadar protein

Analysis of Protein Levels Gunning Method

February 22, 2012

EVENT: Protein Content Analysis Method Gunning

II. OBJECTIVE: Ability to analyze protein levels in test samples of materials / agricultural products using the Gunning


– Tools:

  • Analytical Balance
  • Flasks Kjeldahl
  • Pole mountings
  • Tripod
  • Asbestos Wire
  • Hotplate
  • Bottle Washer
  • Glasses Watches
  • Funnel Glass
  • Measure Glasses
  • Flasks Distillation
  • Pipette drops
  • Erlenmeyer
  • Burette
  • Pipette Volumetry
  • Glass Beaker
  • Pumpkin Measure 250 ml
  • Red Litmus Paper

– Material:

  • Sample Test Material / Product Agriculture
  • Selenium
  • 2 SO 4 Concentrated (98%)
  • Aquades
  • Indicator PP 1%
  • NaOH 25%
  • 0.1 N HCl
  • 0.1 N NaOH
  • NaOH 25%


  1. Considering approximately 3-5 grams of the test sample and about 4 grams of Selenium on the glass watches
  2. Entering into a Kjeldahl flask and add 25 ml of H 2 SO 4 concentrated
  3. Mendestruksi destruction until the solution becomes clear or not too dark
  4. Refrigerate for a few minutes and then add about 150 ml of distilled water
  5. Insert into Measure 250 ml flask, add distilled water until the calibration mark (Solution L1)
  6. Homogenize in a glass beaker
  7. Taking 25 ml solution of L1 and insert into the distillation flask
  8. Adding 3-4 drops of 1% and Indicator PP 25% NaOH dropwise until a pink
  9. But before the distillation flask filled with these materials, making container consisting of Erlenmeyer flask containing 0.1 N HCl at 25 ml and 4-5 drops of 1% PP Indicator
  10. Doing distillation until no alkaline distillate droplets
  11. Titrate using standardized 0.1 N NaOH until the color turns into pink light
  12. Record the titration volume (A ml)
  13. Make a blank test by repeating the procedure 9 s / d 11, which means replacing the L1 solution to 25 ml of distilled water. (Blank titration (B ml))
  14. Calculating Protein Content of the test sample using the formula:

> Rate of nitrogen (% N):

    = (Dilution Factor x (B ml – A ml) x Normality of NaOH standardized x Ar.Nitrogen) x100% / weight of sample (mg)

protein content (% Protein):

    % nitrogen x Conversion Factor Samples


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