Urine analysis

What's it all about?

Doctors can learn a lot about a patient from their urine. For example, they can discover whether the patient has kidney disease or diabetes.

Simple chemistry is used to mimic the look and (amazingly) the smell of urine for a range of tests. It really does look convincing, especially when the technicians bring out brimming containers of warm, faintly yellow liquid!

The tests are for colour, odour, pH, and the presence or absence of protein and glucose.

Student notes

There are four tests to do on each sample of urine:

Examination by eye and nose

Examine the urine carefully by eye and … nose! Comment on the colour of the urine. Try to use words like yellow, amber, dark and pale. Examine the sample for its odour (smell). Also note whether the sample is clear or cloudy.

Record your observations in your Urine Testing Chart.

A dastardly crime has been committed in the vicinity of the toilets. The villain’s urine and samples from four suspects have been collected. Your task is to find out who did it.

Carry out each test on Sample X to make sure you can carry out all the tests properly, then repeat them for Samples A to D and the villain’s sample.

pH testing

Now you need to find out the pH of the unheated urine. Dip a piece of universal indicator paper into the urine. Quickly take it out, and leave it for 30 seconds. Compare the paper colour with the pH colour chart, and note the pH number on your Urine Testing Chart.

Testing for protein

Next, find out if the sample contains protein. You are doing this because protein leaks into the urine if the kidneys are damaged.

Divide the sample equally between two test tubes. Put one tube into the hot water bath, and leave the other at room temperature. After a few minutes, take the test tube out of the water bath, and compare the heated and unheated urine.

If the heated sample is more cloudy, it contains protein. Note your result in your Urine Testing Chart.

Flush away the heated urine, and keep the unheated sample.

Testing for glucose

The last test is to find out if the urine contains glucose, which may indicate that the patient has diabetes. Dip a glucose test strip into the unheated urine sample, and immediately take it out. Count to ten, then check the colour with the colour chart. Record the amount of glucose shown by the colour of the test strip.

Urine Testing Chart

Record your results for Sample X in the first table of your Urine Testing Chart (a simple version is shown below).

Urine Testing Chart
Your name
Universal indicator colour
Unheated sample
Heated sample
Glucose test strip result

Record your results for Samples A to D, and the villain’s sample, in the second table of your Urine Testing Chart (a simple version is shown below).

Sample ASample BSample CSample DVillain
Protein (✓ or ✗)
Glucose (✓ or ✗)

Who was the villain, and why?

Teacher Guide

Activity notes

There is a fair amount of excitement involved in this activity, so it is important to impress upon the students that they should treat the samples following normal laboratory rules. The substances used are low hazard, but you may want to insist on eye protection as a way to remind the students to work sensibly.

Students should carry out the tests on Sample X first. The purpose of this sample is to check the ability of the students to obtain positive results. It is wise to check these before allowing the students to work on the other samples.

The protein test works well, but you might want to use the biuret test instead. Urine glucose test strips are easy to use for glucose testing, and give the activity an authentic feel. However, you may wish to use Benedict’s reagent instead.

The expected results are shown in the table below.

Sample XSample ASample BSample CSample D

The ‘villain’ is your choice of samples A to D.

Health and Safety

When considering carrying out a practical activity with a class, you must check your local health and safety rules. Make an appropriate risk assessment and try the activity yourself first.

Student checklist

Check that you have the following things.

  • 2 × test tubes
  • 1 × test-tube rack
  • 1 × teat pipette
  • Urine Testing Charts (one each)
  • universal indicator paper with pH colour chart
  • glucose test strips with colour chart

Note that you need two different colour charts:

  • one for the universal indicator paper
  • one for the glucose test strips

You will also need access to a hot water bath set at 70 °C.
Take care – remember that this is HOT!

Technician notes

Per group of students:

  • 2 × test tubes
  • 1 × test-tube rack
  • 1 × teat pipette
  • Urine Testing Charts (one per student)
  • universal indicator paper with pH colour chart
  • glucose test strips with colour chart

In the lab

Thermostatically-controlled water bath set at 70 °C, containing a test tube rack (place a warning notice on the water bath).

Artificial urine samples: dissolve the following substances and solutions into 1 dm3 of water, according to the table below. Add a few drops of yellow food colouring to each sample.

Sample XSample ASample BSample CSample D
NaCl /g33333
urea /g555
glucose /g1111
albumin /g111
2M HCl(aq) /cm30.10.2
1M NH3(aq) /cm31

In addition, select one of the samples A to D as the ‘villain sample’. Depending on the volume needed, either make up another sample or divide the chosen sample.

 1 M ammonia solution

Irritant (skin and eyes). Solutions release corrosive and toxic ammonia vapour.