Question

Which one of the following is the most sensitive immunoassay?

• A. Immunoelectrophoresis
• B. Immunofluorescence
• C. Radial immunodiffusion
• D. Radioimmunoassay

Hint:

Radioimmunoassay (RIA) is highly sensitive due to the use of radioactive isotopes. It can detect very low concentrations of analytes, making it ideal for trace analysis.

Answer 1

The Correct Option is D

Radioimmunoassay (RIA) is considered the most sensitive immunoassay technique among the listed options. It uses radioactively labeled antigens or antibodies to detect trace amounts of substances. The high sensitivity is due to the use of radioactive isotopes, which allows for the detection of very small quantities of analytes in biological samples. Hence, statement (D) is correct.
- (A): Immunoelectrophoresis is a technique that separates proteins based on their size and charge using an electric field. While it is useful for separating proteins, it is not as sensitive as radioimmunoassay. Thus, statement (A) is incorrect.
- (B): Immunofluorescence uses fluorescent-labeled antibodies to detect antigens. While sensitive, it is not as sensitive as radioimmunoassay due to lower signal intensity. Hence, statement (B) is incorrect.
- (C): Radial immunodiffusion is a method for quantifying antigens, but it is less sensitive compared to radioimmunoassay because it relies on a diffusion-based process rather than radioactive labeling. Therefore, statement (C) is incorrect.
Thus, the correct answer is (D).