Question

Detection of ______________ adulterant depends on the aldehyde-oxidation reaction of an aromatic amine.

• A. Formalin
• B. Urea
• C. Quaternary Ammonium Compounds
• D. Sodium hypochlorite

Hint:

Associate the term "aldehyde-oxidation" directly with Formalin (formaldehyde), which is the only aldehyde-containing preservative commonly detected in adulterated milk.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Formaldehyde (formalin) is an aldehyde preservative. It is detected in milk through various chemical tests, such as Hehner's test or the chromotropic acid test, which rely on the condensation or oxidation reaction of aldehydes with specific reagents.

Step 2: Detailed Explanation:
- Formalin contains formaldehyde (\( \text{HCHO} \)), which is a highly reactive aldehyde.
- The detection of formaldehyde in milk often involves its reaction with aromatic amines or phenolic compounds in the presence of strong acids (such as concentrated sulfuric acid).
- In these tests, the aldehyde undergoes an oxidation or condensation reaction with the aromatic amine (such as p-phenylenediamine or similar indicators), producing a characteristic colored complex (such as a violet or purple ring).
- Other options like Urea (an amide), QACs (cationic surfactants), and Sodium hypochlorite (an inorganic salt) do not contain aldehyde groups and do not undergo aldehyde-oxidation reactions.

Step 3: Final Answer
The detection of formalin adulterant in milk depends on the aldehyde-oxidation reaction of an aromatic amine.