EXP 12

• What should be observed in a fresh urine sample?


  Color, odor, pH, specific gravity, temperature, weight, and volume
• Why is it important to repeat observations of urine after 1-2 hours?

  To record any changes in color, odor, and pH
• What is the expected result of the biuret formation test for urea?

  Purple/violet color indicating biuret formation
• What is the procedure for testing urea using the biuret formation method?

  Heat urea, add 10% NaOH and 0.1% CuSO₄ after cooling
• What indicates the presence of uric acid in the murexide reaction?

  Yellow/red color on drying, turning purple/violet on adding NH₄OH
• What is the expected result of the nitroprusside test for creatinine?

  Red/pink color if creatinine is present
• What happens to the color in the picric acid reaction for creatinine when acidified with HCl?

  The orange/red color fades with acidification
• What indicates the presence of indican in Obermeyer’s test?

  Blue color in the chloroform layer
• What is the result of the boiling test for albumin in urine?

  White precipitate indicates albumin
• What does a white ring at the junction of urine and concentrated HNO₃ indicate?


  Presence of albumin
• What is the expected result of the Benedict’s test for glucose?

  Red, yellow, or green precipitate depending on glucose concentration
• What indicates the presence of bile acids in Gmelin’s test?

  Green, blue, or violet rings at the urine-acid interface
• What color indicates the presence of acetone in Legal’s test?

  Ruby red color intensifies with added acetic acid
• What indicates the presence of β-hydroxybutyric acid in urine?

  Enhanced red color in H₂O₂-treated tube
• What is the expected result of the heat test for Bence-Jones proteins?

  White precipitate at 40-60°C that disappears at 100°C and reappears on cooling
• What are the average physical properties of urine for an 18-year-old male?

  Pale yellow color, mild odor, pH around 6.0, specific gravity between 1.002 and 1.030
• What are the physical properties observed in urine?

  • Color
  • Odor
  • pH
  • Temperature
  • Specific gravity
  • Weight
  • Volume
• What are the steps for testing nitrogenous constituents in urine?

  1. Urea: Biuret formation test
  2. Uric Acid: Murexide reaction
  3. Creatinine: Nitroprusside test and Picric acid reaction
  4. Indican: Obermeyer’s test
• What are the tests for pathological constituents in urine?

  1. Albumin: Boiling test and Heller’s test
  2. Glucose: Benedict’s test
  3. Bile: Gmelin’s test
  4. Acetone Bodies: Legal’s test and β-hydroxybutyric acid test
  5. Bence-Jones Proteins: Heat test
• Nitrogenous constituents of urine

  Urea: Formation of Biuret

  Uric Acid: Murexide reaction

  Creatinine:

  Nitroprusside (Weyl)

  Picric

  Indican: Obermayer
• What was the focus of Experiment 12?

  Identifying specific compounds through biochemical tests
• What does a bluish-violet color indicate in the Murexide Test?

  Presence of uric acid forming purpuric acid
• What color complex is produced in the Nitroprusside/Weyl’s Test?

  Red-colored complex
• What does a deep orange-red color indicate in the Picric Acid Test?

  Presence of creatinine and sugar
• What color indicates a positive result in Obermeyer’s Test for indican?

  Greenish-blue or indigo color
• What does turbidity in the Boiling Test indicate?

  Presence of albumin
• What forms at the junction in the Nitric Acid Test for albumin?

  A white ring
• What color change occurs in the Benedict’s Test for glucose?

  From blue to red
• What does Gmelin’s Test for bile reveal?

  Various colored rings at junctions
• What color indicates a positive result in the Sodium Nitroprusside Test/Legal’s Test?

  Ruby-red color
• What is indicated by a ruby-red color in the β-hydroxybutyric Test?

  Presence of acetone
• What characterizes the Bence-Jones Protein Test?

  Precipitation at low temperatures
• What happens to the precipitate in the Bence-Jones Protein Test at higher temperatures?

  Dissolution occurs