- use to detect presence of peptide bonds
- Reagent: NaOH, CuSO4
- Positive result: Blue → Pink (peptide bonds are present, 2 or more amino acids are present)
- Negative result: Blue (only 1 amino acid is present or none).
Biuret Test
test for x-amino acid
Reagent: Ninhydrin soln
Positive: (1:violet 2: yellow
Ninhydrin Test
Detects presence of aromatic side chains
reagent: HNO3
Positive: yellow ppt.
Xanthoproteic Test
Detects amino acids that contain phenol group
Positive: Brick red/ old rose; presence of tyrosine
Millon’s Test
Detects the presence of indole rings
positive: violet ring
Hopkins-Cole Test
detects the presence of arginine.
* Positive: red/wine color
* Reagent: -napthol
Sakaguchi Test
used to find sulfur containing amino acids.
* Ex. Cysteine
* Positive: Red
Nitroprusside Test
- detects tyrosine or histidine
- Positve: Red color
- Negative: Glycine
Pauly test
A common technique used to identify compounds,
determine purities. Also used to separate or differentiate
substances according to their polarity.
Thin layer chromatography
Semi-quantitative method
Thin layer chromatography
special finely ground matrix (silica gel,
alumina) is coated on a glass plate or a metal or plastic film
as a thin layer.
Stationary phase
