Chapter 2 Exercises
Gas chromatography is a widely used analytical technique for separating and analyzing volatile compounds in a mixture. The basic principle relies on the differential partitioning of components between two phases: a stationary phase and a mobile phase. In gas chromatography, the mobile phase is an inert gas, such as helium or nitrogen, which carries the sample through the column. The stationary phase, typically a liquid coated on a solid support, interacts differently with each component of the mixture. As the sample moves through the column, the components are repeatedly dissolved into and volatilized from the stationary phase, depending on their affinity for it. This process, known as partitioning, leads to the separation of the components based on their differing interactions with the two phases. Some methods also involve adsorption and desorption, especially in gas-solid chromatography. Once separated, the components reach the detector, where they are identified and quantified.
What are the basic equipment of a gas chromatograph, and what are their functions? A typical gas chromatograph consists of several key components. First, the pneumatic system provides and regulates the flow of the carrier gas, ensuring a stable and continuous supply. Next, the injection system introduces the sample into the system. It usually includes a syringe for liquid samples and a heated vaporization chamber that converts the sample into a gaseous state before it enters the column. The separation system, which is the heart of the instrument, contains the chromatographic column where the actual separation occurs. The temperature control system ensures that the column and other parts of the instrument maintain precise and stable temperatures, which is crucial for consistent results. Finally, the detection and recording system identifies the separated components as they elute from the column and records the data for analysis. Together, these components work in harmony to provide accurate and reliable chromatographic results.
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