Tests for Organic Compounds
Iodine Test - Iodine changes from a yellow-brown to blue-black in the presence of starch. Monosaccharides and disaccharides do not react with iodine reagent.
  1. Please record your hypothesis of whether you think the sample will have starch in it in the table below.
  2. Get 5 test tubes. Label the tubes A, B, C, D, & E with a with a pencil on a small piece of masking tape..
  3. Add a dash of sample to be tested in each tube (this test is not amount sensitive) and add 1 to 2 cm of water in the bottom of the tube.
  4. Record the color of the contents of each well in the table below.
  5. Add 4 drops of Iodine to each sample.
  6. Record the color of the contents of each test tube in the data table. A dark blue, black, or purple indicate starch is present.
  7. Record the presence (+) or absence (-) of starch in the data table.
Iodine Test for Starch (positive test = substance turns dark blue)
Well Contents
Original Color
Final Color
Hypothesis: Will starch be present? yes (+) or no (-)
Starch present?
yes (+) or no (-)
A) Water
B) Starch
C) Milk
D) Tofu
E) Apple

Biuret Test for Proteins - Biuret reagent is a light blue solution which turns purple when mixed with a solution containing protein.

  1. Record your hypothesis of whether you think protein will (+) or will not (-) be present in data table.
  2. Label 5 test tubes with a pencil on a small piece of masking tape.
  3. Add a small amount of sample to each and a small amount of water (1 to 2 cm at bottom of tube).
  4. Add 10 drops of Biuret reagent to each tube (CAUTION: Biuret's reagent will damage your skin if it gets on it. Rinse it with water immediately upon contact.).
  5. Gently tap the test tube against your hand to stir.
  6. Wait 2 minutes.
  7. Examine the color change carefully. A purplish or pink color indicates the presence of protein.
  8. Record your observations in the table below. Indicate the presence (+) or absence (-) of protein in the sample.
Biuret Test for Proteins (positive test = solution turn pink to purple)
Well Contents
Original Color
Color after 2
minutes
Hypothesis: Will protein be present? yes (+) or no (-)
Protein present?
yes (+) or no (-)
A) Water
B) Tofu
C) Milk
D) Starch
E) Apple

Benedicts Test for Monosaccharides - Benedicts solution will turn orange when simple sugars are present.

  1. Set up a row of 4 test tubes. Label the tubes with a wax pencil.
  2. Add a dash of each of the sample to be tested into the tubes with 1 cm of water.
  3. Add 2 ml (40 drops) of Benedict's solution.
  4. Mix the contents by gently tapping the tube against the palm of your hand.
  5. Record the color of the contents of each tube in the table below.
  6. Place all the tubes in a beaker of boiling water for 3 minutes.
  7. Remove the tubes and allow to cool for 3 minutes.
  8. Observe each tube carefully. Record in the table the color and amount of any precipitate formed. For the amount of precipitate use symbols: 0, +, ++, or +++. Blue shows no simple sugar (0). Green indicates a small amount (+ or ++). Orange indicates a large amount of simple sugar (+++)
Benedict's Test for Monosaccharides (positive test = greenish to orange color change)
Tube Contents
Original Color
Final Color
Hypothesis: Will simple sugars be present?
yes (+) or no (-)
Amount of
Precipitate or Orange Color?

0, +, ++, +++
A) Water
B) Glucose
C) Apple
D) Milk

Brown Bag Test for Lipids - When a small amount of lipid is dropped on or smashed into the paper of a brown paper grocery sack it will cause it to become translucent. When held up toward a light, lipids allow one to see the light coming through the sack.

  1. Take each substance and either drop it on, or smash it into, the brown paper bag (a small amount of each substance will do).
  2. Hold it up to the light after allowing several minutes for the substances to soak in.
  3. Observe each spot carefully to check if light is allowed through (translucent) or not (opaque) and record your results.
Brown Paper Bag Test for Lipids (positive test = brown paper turns translucent = lets light through)
Paper Contents
Translucent or Opaque?
Hypothesis: Will simple lipids be present?
yes (+) or no (-)
Were lipids present?
yes (+) or no (-)
A) Water
B) Butter
C) Apple
D) Milk
E) Tofu