Retention time (tₐ) in Gas Chromatography (GC) is the time a compound takes to travel through the column from injection to the detector.
Simple explanation:
- When you inject a sample, each compound moves through the column at a different speed.
- The detector records a peak when the compound exits the column.
- The time from injection to the peak is called the retention time.
Key Points:
- Depends on:
- Interaction with the stationary phase
- Boiling point of the compound
- Column temperature
- Carrier gas flow rate
- Useful for:
- Identifying compounds (each has a characteristic retention time)
- Checking reproducibility of analysis
In short:
Retention time is the time a compound spends in the GC column before detection — it helps identify and compare substances.