Question

Which of the following method is preferable for collecting blood clot for DNA evidence samples ?

• A. Collect clot in sterile tube and add equal volume of normal saline
• B. Collect in EDTA tube
• C. Collect clot in sterile tube and add equal volume of PBS
• D. Thoroughly air dry at room temperature and roll it in clean paper

Hint:

Biological samples → Keep dry, avoid moisture → Paper packaging preferred over plastic.

Answer 1

The Correct Option is D

Concept: Proper collection and preservation of biological samples are essential to prevent degradation of DNA. Blood clots require careful handling to maintain DNA integrity.

Step 1: Understanding DNA degradation risks.
DNA can degrade due to moisture, microbial growth, and enzymatic activity. Therefore, proper drying and storage are critical.

Step 2: Importance of air drying.
Air drying removes moisture, which prevents bacterial growth and enzymatic degradation of DNA.

Step 3: Proper packaging method.
After drying, the sample should be wrapped in clean paper (not plastic) to allow air circulation and avoid moisture accumulation.

Step 4: Evaluating other options.

• Adding saline or PBS – Introduces moisture, increasing degradation risk.
• EDTA tube – Suitable for liquid blood, not clotted samples.

Step 5: Final evaluation.
Thus, drying and storing in clean paper is the best method. Final Conclusion:
Hence, the correct answer is option (4).