Turbidimetry is used to measure which of the following?

• A. Protein measurements, bacterial growth in broth, and clot detection
• B. Chloride concentration
• C. Antigen-antibody complexes
• D. Serum protein separation

Answer: (A)

Turbidimetry measures how much light is blocked as it passes through a solution, which depends on how many suspended particles are in the sample. More particles scatter light, so less light reaches the detector and the turbidity reading goes up.

This makes it especially useful when the sample contains particles that can grow or form networks. Protein-containing solutions can become turbid as protein concentration increases, so turbidimetry can be used to estimate protein amount in some assays. Bacterial cultures in broth become more turbid as cells multiply, providing a simple way to monitor growth. When a clot forms, a fibrin network plus cells creates particles that scatter light, allowing turbidity to track clot development.

Chloride concentration isn’t determined by light scattering of suspended particles, so turbidimetry isn’t a standard method for that measurement. Serum protein separation relies on methods like electrophoresis or chromatography to separate proteins by size and charge, not on measuring turbidity. Antigen–antibody complexes can cause turbidity in some assays, but the classic, most straightforward uses of turbidimetry align with measuring particulates like proteins, growing bacteria, and clots.