Overview of Chromatography (A2 Only)
Chemistry: AQA A Level, topic 6.10.1
Basics of Chromatography
Chromatography is a common separation and product identification technique used by chemists.
Basics of chromatography
- Chromatography works to separate substances based on their interactions with a mobile and stationary phase.
- The mobile phase is typically a solvent.
- The stationary phase is typically a solid support.
Process of chromatography
- A substance is allowed to interact with both the mobile and stationary phase in either a column or a plate.
- The more a substance interacts with the stationary phase, the longer it will take to reach the bottom of the column or plate - we say it will take longer to elute.
Separation or identification
- Chromatography can use the different elution times of different substances to:
- Separate substances as they leave the column or plate at different times.
- Identify substances using Rf values - something we will see later.
Retention time
- In gas chromatography, we typically measure the time taken for the substance to elute from the column - this is called the retention time.
- Substances with a large retention time interact strongly with the stationary phase.
- Substances with a small retention time interact weakly with the stationary phase.
Test yourself on Overview of Chromatography (A2 Only)
A stationary phase will interact more/less with different substances. What does a stronger interaction result in?