Question

Observation of Rhumann’s purple is a confirmatory test for the presence of:
A. Starch
B. Reducing Sugars
C. Protein
D. Cupric Acid

Answer 1

Hint: The production of a yellow colored product upon the addition of nitric acid is a test for the presence of tyrosine or tryptophan in a protein.

Complete step by step answer:
Proteins are macromolecules which are solvent (suspended) in water. Proteins are least solvent in water at their isoelectric focuses and are more dissolvable at sequential pH's. The solubility at pH is unique in relation to the isoelectric point seems, by all accounts, to be because of the presence of an overabundance of cationic gatherings or anionic gatherings on the outside of the protein. In the event that the protein is, for example, adversely charged at a pH bigger than the isoelectric point, when two proteins chance upon one another, the net negative charge repulses them and they don't total as one would anticipate from huge atoms. Nonetheless, at the protein's isoelectric point there is no net charge.
Ninhydrin Test: The Ninhydrin Test is a test for amino acids and proteins with a free \[-N{{H}_{2}}\] group. When such an \[-N{{H}_{2}}\] group reacts with ninhydrin, a purple-blue complex is formed.

The ninhydrin test is employed by SSDs for residual protein detection. SSDs use rayon swabs wetted with water, to clean 'cleaned' instrument surfaces before they are dunked in ninhydrin and warmed to about \[{{60}^{\circ }}C\] for as long as 60 minutes. On the off chance that the swab turns purple, at that point protein tainting is recommended, requiring the instrument to be rewashed. The positive control is an answer of the dibasic amino corrosive arginine. Such ninhydrin packs are broadly utilized.

Hence, the correct option is C. Protein

Note:
Ninhydrin is utilized in numerous bioanalytical strategies especially for amino corrosive investigation techniques. Ninhydrin responds with the \[\alpha -\]amino gathering of essential amino acids creating 'Ruhemann's purple'. The chromophore shaped is the equivalent for all essential amino acids. The power of the shading frame relies upon the number and compound nature of the amino gatherings being broken down.