Biochemical Tests

Question 1

What is the test for protein ?

Answer 1

Biuret reagent
Positive result turns purple/lilac

Question 2

What is the test for lipids ?

Answer 2

Ethanol, shake. Water, shake.
Positive test= white emulsion.

Question 3

What is the test for reducing sugars?

Answer 3

Benedict’s reagent in 95’C water
Positive result = brick red precipitant.

Question 4

What is the test for non reducing sugars?

Answer 4

First test for reducing sugars.
Then in another test tube, add an acid ( e.g. HCl) to the sugar sample and place in water bath ( 95’C ) for 5 mins. Slowly add sodium hydrogen carbonate to the tube to neutralise the acid. Test with pH paper as benedicts wont work if too acidic.
Add benedicts solution and place in 95’C water it should turn brick red precipitant.