Urinalysis Lab

Urinalysis Lab Introduction All organisms produce waste that must be removed. In humans, urine is the fluid produced by the kidneys as they remove nitrogenous waste from the blood. Urine is a watery fluid containing excess salts, nitrogenous wastes, and a variety of organic molecules. The concentration of each of these substances depends on the person’s health and diet. Physicians can evaluate the general health of an individual by testing the chemical composition of urine. Ions such as phosphate and chloride are normally found in urine, but glucose molecules are a symptom of diabetes. Albumin, a protein, is sometimes found in the urine after heavy exercise, but the presence of albumin over an extended period can be a symptom of a kidney infection. The analysis of a using sample is called urinalysis and includes a physical, chemical and visual examination. In this investigation you will:

a. Learn how to run the chemical test for detecting the presence of glucose (sugar), chlorides (salts), albumin (proteins), and phosphate. b. Perform four tests on urine samples having known chemical makeup. c. Perform four tests on urine samples having unknown chemical makeup. Pre-Lab Discussion 1. In each analysis two samples are tested, one with the chemical and one without it. What is the purpose of testing a sample without the chemical?

2. Which of the tests require heating of the reagent with the sample in a water bath? 3. What substance is detected by reaction with Benedict’s solution? What color will the solution turn to indicate a positive reaction?

4. When is the silver nitrate reagent used? What are you going to look for to indicate a positive reaction with each test? 5. For which test will you use the Biuret solution? What color will the solution turn to indicate a positive reaction? Materials • •

• • •

Hotplate Beaker Benedict’s Solution Biuret Solution Water

• • • • •

Test tubes- 8 Test tube holder Silver nitrate solution 5 mL syringe Acetic acid

•

• •

Urine- unknown Urine with glucose, chlorides, albumin, calcium Urine without glucose, chlorides, albumin, calcium

1

Procedure: Part A. Glucose (sugar) Test

Benedict’s solution changes from its original blue color to green, yellow, orange or red in the presence of glucose when heated. Benedict’s solution remains its original blue color if no glucose is present. 1. Place two test tubes on the test tube rack. Label one G (for glucose). Allow the other to remain unlabeled as it will serve as the control. 2. Add 2 mL of Benedicts solution to each of the two test tubes. 3. Add 2 mL of urine with glucose to the test tube labeled G. Add 2 mL of urine without glucose to the unlabeled test tube. Note the appearance of the solution in each test tube. Record your information in Data Table 1. 4. Place the test tubes in the hot water bath for three minutes or until you see a color change. 5. Remove the test tubes from the hot water bath using a test tube holder. Place the test tubes in the test tube rack. Note the appearance of the solution in each test tube. Record your information in Data Table 1. Part B. Test for Chloride

Several drops of silver nitrate solution added to chlorides cause a white cloud (precipitate) to form in the liquid. If no chlorides are present, no white cloud will form. 1. Place two test tubes on the test tube rack. Label one Cl (for chloride). Allow the other to remain unlabeled as it will serve as the control. 2. Add 2 mL of urine with chlorine to the test tube labeled Cl. Add 2 mL of urine without chloride to the unlabeled test tube. Note the appearance of the solution in each test tube. Record your information in Data Table 2. 3. Carefully add three drops of silver nitrate solution to each test tube. Observe the top surface of the liquid in each test tube immediately after silver nitrate is added. Record your information in Data Table 2. Part C. Albumin (Protein) Test

If albumin is present in a urine sample, the sample will turn purple or pink in the presence of Biuret. If no albumin is present, no color change will occur. 1. Place two test tubes on the test tube rack. Label one A (for albumin). Allow the other to remain unlabeled as it will serve as the control. 2. Fill half of the test tube labeled A with the simulated urine sample with albumin. Fill half of the unlabeled test tube with the simulated urine sample without albumin. 3. Add 5 drops Biuret to each test tube. 4. Note the appearance of the solution in each test tube and record your information in Data Table 3. Part D. Test for Calcium

If a urine sample contains calcium, it will form a white precipitate in the presence of silver nitrate. If there is not calcium in a urine sample, there is no calcium present. 1. Place two test tubes on the test tube rack. Label one Ca (for calcium). Allow the other to remain unlabeled as it will serve as the control. 2. Fill half of the test tube labeled Ca with the simulated urine sample with calcium. Fill half of the unlabeled test tube with the simulated urine sample without calcium. 3. Add two drops of silver nitrate to each tube. Note the appearance of the solution in each test tube and record your information in Data Table 4. Also note how this reaction is different than the reaction of silver nitrate with chloride in the urine. Part E. Testing an Unknown Urine Sample

1. Clean all of your test tubes from Part A through D. Reuse these test tubes to perform your chemical tests on your unknown sample of urine. 2. Obtain an unknown sample of urine. Be sure to mark the number of your unknown on Data Table 5. 3. Perform the glucose, chloride, albumin and calcium test on the unknown. You will need to use a new test tube for each chemical test. Use the proper amount of urine and chemicals needed to run each test. Make sure that all test tubes are clean. Use parts A through D as a guide.

2

4. Record all your results in Data Table 5. Data Table 1: Substance

Appearance before heating

Appearance after heating

Appearance before adding silver nitrate

Appearance after adding silver nitrate

Appearance before adding Biuret

Appearance after adding Biuret

Appearance before adding silver nitrate

Appearance after adding silver nitrate

Sample with glucose Sample without glucose Data Table 2: Substance Sample with chlorine Sample without chlorine Data Table 3: Substance Sample with albumin Sample without albumin Data Table 4: Substance Sample with calcium Sample without calcium Data Table 5: Composition of Unknown Simulated Urine Sample # _____ Test

Present or Absent?

Glucose Chlorine Albumin Phospha te

Use the information in Data Table 5 to research the following information: 1. What might cause this (the presence of the substance) to happen? 2. What may result because of this? 3. What can be done to “fix” the problem? 4. Tell us any other pertinent information about finding the substance in urine. 3

5. You will want to listen to the other groups when they present their information on their substance in the urine! Make note of these next to your data tables! You might want to know it for the test

4