Test For Presence Of Urea In Urine

Aim

To perform a test detecting the presence of urea in the given sample of urine.

Theory

What is Urine? Describe human urine.

Urine is produced by the kidney. It is a liquid waste that needs to be eliminated from the body. The kidneys eliminate the wastes from the bloodstream. In humans, urine is a yellowish liquid containing water and several other chemical components such as uric acid, urea, traces of enzymes, hormones, and carbohydrates.

Production of Urea

It is produced naturally by the body while the proteins are disintegrated during which amino groups are eliminated from the amino acids that are in the proteins. The eliminated amino groups are converted into extremely toxic ammonia and furthermore into urea by the liver. The urea moves into the kidneys, where it is finally eliminated from the body.

Detecting urea

For detection of urea in the urine sample, urease tests are performed. Urease is an enzyme that carries out the decomposition of urea into carbon dioxide and ammonia. Addition of an alkaline substance such as ammonium carbonate causes it to turn into an alkaline solution from slightly acidic urine.

1. Sodium Hypobromite Test

Material Required

• Dropper.
• Test tube.
• Urine sample.
• Measuring cylinder.
• Sodium hypobromite solution.

Procedure

• Take a clean and dried test tube.
• With the help of a measuring cylinder, add 2ml urine sample into the test tube.
• To the same test-tube add 2 to 3 drops of sodium hypobromite solution using a dropper.
• Mix the solution well.
• Observe the changes.

Observation And Conclusion

The presence of urea in the given urine sample is indicated by the presence of brisk effervescence of nitrogen around the test tube.

2. Urease Test

Material Required

• Spatula.
• Dropper.
• Urine sample.
• 1% acetic acid.
• 2%  of Na₂CO_3.
• Urease powder.
• Measuring cylinder.
• Phenol red indicator.

Procedure

• Take a clean and dried test tube.
• With the help of a measuring cylinder, measure and add 5ml urine sample into the test tube.
• To the sample test tube, add 4 to 5 drops of the phenol red indicator using a dropper.
• With the help of another dropper, add drops of 2% Na₂CO₃ solution drop-wise until the pink colour starts developing in the test tube.
• With the help of another dropper, add a few drops of 1% acetic acid. Add drop-wise until the pink colour disappears.
• With the help of a spatula, add little urease powder into the urine sample test tube.
• Now shake the test tube slowly until the urease powder get mixed.
• Now observe the changes.

Observation And Conclusion

The existence of urea in the given sample of urine is indicated when a red or pink colour appears in the solution.

Learn more in detail about the urine, presence of urea in urine, other related topics and experiments at BYJU’S Biology.

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