Notes On Chromatography

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Chromatography techniques
Chromatography is an analytical technique used for separation of different components from a given mixture. The basic principle is the characteristic distribution or partition coefficient denoted as Kd which is due to the specific distribution of the analyte between two immiscible phases, the mobile and stationary phases.
In a chromatographic system the stationary phase may be a solid, gel, a solid mixture or a liquid mixture which is immobilized. The mobile phase may be a gas or a liquid and is passed through the stationary phase to which the analyte is applied before passing the mobile phase through it. The differential affinity towards the mobile phase and stationary phase of different components of the sample mixture
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The type of carrier gas depends on the type of detector used. Typical carrier gases are helium or hydrogen with safety precautions and nitrogen or argon. The carrier gas must be very pure (greater than 99.995%). The carrier gas carries the sample through a gas chromatography column where it is separated into individual components of sample mixture. The carrier gas system contains a molecular sieve to remove water and other impurities. Traps are another option to keep the system pure and optimum sensitive and removal traces of water and other contaminants. A two stage pressure regulation is required to use to minimize the pressure surges and to monitor the flow rate of the gas. To monitor the flow rate of the gas a flow or pressure regulator was also require onto both tank and chromatograph gas inlet. This applies different gas type will use different type of regulator. The carrier gas is preheated and filtered with a molecular sieve to remove impurities and water prior to being introduced to the vaporization chamber. A carrier gas is typically required in gas chromatography system to flow through the injector and push the gaseous components of the sample onto the gas chromatography column, which leads to the
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