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Differences between TCD and FID in GC

The key differences between Thermal Conductivity Detector (TCD) and Flame Ionization Detector (FID) in gas chromatography:

1. Detection Principle

 - TCD (Thermal Conductivity Detector): Measures changes in the thermal conductivity of the carrier gas caused by the presence of analytes. It relies on the heat transfer properties of the gas stream.

 - FID (Flame Ionization Detector): Utilizes the ionization of organic compounds in a flame. The combustion of analytes in a hydrogen flame produces ions that are detected.

2. Sensitivity

 - TCD: Generally less sensitive compared to FID. It is suitable for detecting less volatile and non-destructive compounds.

 - FID: More sensitive, especially for organic compounds. It is often used for trace-level analysis.

3. Selectivity

 - TCD: Responds to a wide range of compounds, both organic and inorganic, providing less selectivity.

 - FID: Highly selective for organic compounds, making it suitable for specific compound identification.

4. Destructive vs. Non-destructive

 - TCD: Non-destructive. It does not consume or alter the analyte during detection.

 - FID: Destructive. The analyte is burned in the hydrogen flame during detection, making it a consumptive process.

5. Application Areas

 - TCD: Commonly used for general analysis, including inorganic gases and less volatile compounds.

 - FID: Widely applied in environmental, petrochemical, and forensic applications where sensitivity and specificity for organic compounds are crucial.

6. Response Time

 - TCD: Typically has a faster response time compared to FID.

 - FID: May have a slightly longer response time due to the combustion process.

These differences highlight the distinct characteristics and applications of TCD and FID in gas chromatography.

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Resource Person: Abu Talha Bin Dil Chowdhury 

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