Urinalysis Lab

Target Audience 9 - 12
Student Handout Version

Background Notes: Urine and other body fluids can contain information useful to a crime investigator to provide inferences, clues or evidence to link a suspect to a crime scene. Body fluids can include saliva, mucous, semen, vagina fluid, breast milk, or urine. These fluids can carry metabolites (waste products), drugs, medicines, AB and Rh antigens, proteins, hormones, salts (electrolytes), and sugars. There exists a secretory gene (Se) which is found in about 80% population independent of blood type, i.e. a person could be Type A and Se or Type B and Se, etc. This gene interacts with blood type genes and determines your ability to secrete your blood type antigens into other fluids. In other words, secretors put blood type antigens into the blood and body fluids while non-secretors put little to no blood type antigens into body fluids. Persons who are secretors can have their body fluids tested for blood type. Secretors tend to have stronger immune systems, therefore it is better to be a secretor that a non-secretor.

Urine is 95% water and 5% other dissolved or suspended substances including metabolites (waste products), drugs, medicines, A, B, and Rh antigens, proteins, hormones, salts (electrolytes), and sugars. A person produces 0.6 to 2.5 liters of urine depending on the person's intake and environment, i.e. temperature and humidity. If a person is diabetic, their urine may contain high levels of glucose. The presence of protein in the urine often indicates some type of illness.

Knowledge and Skills:

  • Students should be able to design a data table.
  • Students should be able to determine the density of a liquid.
  • Students should know how to use a balance, graduated cylinder and a table top centrifuge.
  • Students should know basic lab safety.
Fundamental Understanding:
  • Urine is a body fluid that contains many different types of identifiable substances, including proteins, sugars, electrolytes, and metabolites.
Essential Questions:
  • How can urine from different individuals be identified?
  • What substances may be found in urine?
National Standards (grades 5-8) content A:
  • Students should be able to do scientific inquiry through scientific investigations.
  • Students should be able to design and conduct a scientific investigation.
  • Students should be able to use appropriate tools and techniques to gather, analyze and interpret data.
National Standards (grades 9-12) content Standard A:
  • Students should develop the abilities to do scientific inquiry.
  • Students should develop an understanding about scientific inquiry.
National Standards (grades 9-12) content Standard B:
  • Students should develop an understanding of the structure and properties of matter, chemical reactions and interactions of energy and matter.
Purpose: To analyze different simulated urine samples for specific gravity, pH, color, glucose and protein.

Safety Precautions:

  • Do not drink anything in the lab.
  • Wash hands after the experiment.
Materials:
  1. Centrifuge
  2. 20 ml pyrex test tubes
  3. Hot plates
  4. 250 ml beakers (for hot water baths)
  5. 100 ml beakers (for urine samples)
  6. Benedict's Solution
  7. pH paper
  8. Samples of synthetic urine
  9. Graduated cylinders or pipettes to measure voumes
Procedure:
  1. Obtain crime scene urine and urine from the 2 suspects
  2. Make a Data Table for the three samples which will include the 4 tests: specific gravity, pH, albumen (+ or -), glucose (+ or -), and the observations of color, odor and clarity.
    1. TEST 1: Determine specific gravity (density) using a balance and graduated cylinder. Record observations of mass, volume and calculate the specific gravity i.e. density.
    2. TEST 2: Determine the pH of the urine samples using pH paper and record results.
    3. TEST 3: Test for albumin: centrifuge 10-15 ml of each urine sample (label each test tube with water proof pen), remove supernatant into 2 clean test tubes. Place one test tube in a hot water bath for 2-4 minutes and compare clarity with original sample. If the heated sample becomes more cloudy then albumin is present (record a + in the data table). Repeat for other samples.
    4. TEST 4: Test for glucose: Add 10.0 ml of each sample to a labeled pyrex test tube, then add 10 drops of Benedict's solution to each of the 3 samples. Place all three test tubes into a hot (not boiling) water bath. Observe and record color. If the blue changes to yellow or gold, then glucose is present (put a + in your data table).
References:
"Biology" fifth edition Neil A. Campbell, Jane B. Reece, and Lawrence G. Mitchell, Addison Wesley Longman. ISBN 0-8053-6566-4

"Crime Scene Investigations - Real Life Science Labs for Grades 6-12", p. 127, by Pam Walker and Elaine Wood ISBN 0-87628-135-8 Prentice-Hall (Simon and Schuster) by The Center for Applied Research in Education

Interesting website on urine:
http://www.heartlandhealing.com/pages/archive/urine_therapy/

Teacher Notes:

  1. Students need approximately 60 minutes to perform these tests.
  2. Purchase synthetic urine (Fisher Scientific) or make different urine from the following recipes based on water with yellow foodcoloring:
    1. Normal urine:160 ml of water + drops of yellow food coloring + 2.0 grams NaCl.
    2. Add 40 ml of apple juice to 66 ml of normal urine A
    3. Add a few drops of egg white (albumin)
    4. Add dissolved glucose, a monosaccharide (sucrose, a disaccharide, does not work)

  3. A crime scene scenario: a jar of urine has been found in the basement of a house that has been robbed. Two suspects have been detained by the police, and urinalysis from the two suspects is required, Urine from the crime scene and suspect two both test positive for protein. Additional forensic evidence needs to be obtained in order to convict suspect number 2.

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