B
Chromatography
Because the principle of Chromatography is to separate various components of substances on the basis of their solubility in water

Chromatography is the technique used to separate drugs from blood.

Explanation:
Chromatography is a widely used technique in various fields, including forensic science and medicine, to separate and analyze different components of a mixture. In the context of drug analysis, chromatography is particularly useful for separating drugs from biological samples, such as blood.

Principle of Chromatography:
Chromatography works on the principle of differential migration of components in a mixture between a stationary phase and a mobile phase. The stationary phase can be a solid or a liquid that is fixed in a column or on a plate, while the mobile phase is a liquid or a gas that flows over the stationary phase.

Process of Separating Drugs from Blood using Chromatography:
When analyzing drugs in blood, chromatography is typically performed using liquid chromatography techniques, such as high-performance liquid chromatography (HPLC). The process involves the following steps:

1. Sample Preparation: The blood sample is first collected and prepared for analysis. This may involve dilution, extraction, or other sample treatment procedures to isolate the drugs from the blood matrix.

2. Injection: A small volume of the prepared sample is injected into the chromatography system. This can be done manually or using automated sample injectors.

3. Separation: The injected sample enters the chromatography column, which contains the stationary phase. The drugs in the sample interact with the stationary phase based on their chemical properties, leading to differential migration. Each drug component separates into individual peaks as they elute from the column.

4. Detection: As the separated drug components elute from the column, they pass through a detector. The detector measures the concentration of each drug component and generates corresponding signals.

5. Data Analysis: The signals generated by the detector are recorded and analyzed using chromatography software. The software processes the data, calculates the retention time of each drug component, and identifies the drugs based on reference standards or spectral matching.

6. Quantification: The concentration of drugs in the blood sample can be determined by comparing the peak areas or heights of the drug components with calibration curves generated using known standards.

Advantages of Chromatography:
- Chromatography is highly selective and can separate drugs with similar structures or properties.
- It allows for the detection and analysis of multiple drugs simultaneously.
- The technique provides accurate quantitative results.
- Chromatography can be used for both qualitative and quantitative analysis of drugs in blood samples.

In conclusion, chromatography is the most suitable technique for separating drugs from blood samples due to its selectivity, sensitivity, and ability to separate complex mixtures.