Solution:
Qualitative test for proteins
Biuret test: The presence of proteins is detected by the biuret test, which changes the colour of the solution from light blue to purple.
Qualitative test for fats and oils
Grease test for oils: On blue paper, certain oils leave a translucent stain. This test can be done to find out if there are any oils or fats present.
Qualitative test for amino acids
Ninhydrin test:
Upon adding ninhydrin reagent to the solution, colour of the solution turns to pink, purple or blue based on the type of amino acid.
| Test | Name of item | Procedure | Result | Conclusion |
| Biuret’s test | Fruit juice | Juice + biuret’s reagent | Change of color from light blue to purple | Presence of protein |
| Saliva | Saliva + biuret’s reagent | Change of color from light blue to purple | Presence of protein | |
| Sweat | Sweat + biuret’s reagent | Colour does not change | Absence of protein | |
| Urine | Drops of urine + biuret’s reagent | Change of color from light blue to purple | Presence of protein | |
| Grease test | Fruit juice | Few drops of juice on brown paper | Translucent spot not observed | Absence of oils and fats |
| Saliva | Few drops of saliva on brown paper | Translucent spot not observed | Absence of oils and fats | |
| Solubility test | Sweat | Water added with sweat | Oil presence | Fats or oils can be present |
| Urine | Water added to a few drops of urine | Slight oily presence | Fats may or may not be present | |
| Ninhydrin test | Fruit juice | Juice+ninhydrin reagent (boil for few minutes) | Change of color from no color to purple, pink or blue | Presence of amino acids |
| Saliva | saliva+ninhydrin reagent (boil for few minutes) | Change of color from no color to purple, pink or blue | Presence of amino acids | |
| Sweat | sweat+ninhydrin reagent (boil for few minutes) | No color change | Absence of amino acids | |
| Urine | urine+ninhydrin reagent (boil for few minutes) | Depending upon type of amino acid, colourless solution changes to purple, pink or blue color | Presence of amino acids |