For blood and urine, preservative used is
**Core Concept**
The question is testing the knowledge of preservatives used in laboratory settings for blood and urine samples. These preservatives are essential for maintaining the integrity of the sample and preventing degradation of the analytes.
**Why the Correct Answer is Right**
The correct answer is **Thimerosal** (Option C). Thimerosal is a mercury-containing organic compound used as a preservative in vaccines and in some laboratory settings to prevent bacterial and fungal growth in blood and urine samples. It acts by denaturing proteins and disrupting cell membranes, thereby inhibiting the growth of microorganisms.
**Why Each Wrong Option is Incorrect**
* **Option A:** is not a commonly used preservative in laboratory settings.
* **Option B:** is not typically used for preserving blood and urine samples.
**Clinical Pearl / High-Yield Fact**
Thimerosal is also used as an antimicrobial agent in some vaccines, but it has raised concerns due to its potential neurotoxic effects. It is essential to handle and dispose of thimerosal-containing products according to laboratory safety protocols.
**Correct Answer: Correct Answer: C. Thimerosal**