The procedure for Tollen’s test is:
- Put 1 mL of silver nitrate in test tube
- Add 1 drop of sodium hydroxide solution to the test tube
- Shake the test tube.
- Observe dark brown precipitate
- Add ammonium hydroxide dropwise to the test tube until the solution becomes colourless again
- Add 2-3 drops of the sample
- Pick up the test tube with the tongs/holder
- Put the test tube in the water bath for 5 minutes
- Using the tongs, take test tube out of water bath and put in tube rack
- Observe formation of silver mirror.
- Add dilute nitric acid and drain off the solution with an excess of water to prevent explosive silver nitride forming.
Figure 1 - Tollen's test procedure for detecting the presence of reducing sugars in a sample.