Gas chromatography GC is a powerful analytical technique used to separate, identify, and quantify different organic compounds in a given mixture. It is based on the principle of partitioning of compounds between a stationary phase usually a solid or a liquid coated on a solid support and a mobile phase an inert gas, such as helium, nitrogen, or hydrogen . The separation occurs due to the differences in the interaction of the compounds with the stationary phase, which results in different retention times for each compound.Here's a step-by-step process on how gas chromatography can be used to determine the composition and concentration of different organic compounds in a given mixture:1. Sample preparation: The mixture containing the organic compounds is prepared in a suitable solvent, and a small volume usually in the microliter range is injected into the gas chromatograph.2. Sample injection: The sample is injected into the injection port of the GC, where it is rapidly vaporized and mixed with the carrier gas mobile phase . The temperature of the injection port is usually set high enough to ensure complete vaporization of the sample.3. Separation: The vaporized sample is carried by the mobile phase through the column, which contains the stationary phase. The organic compounds in the mixture interact with the stationary phase to varying degrees, depending on their chemical properties, such as polarity, molecular size, and functional groups. This results in the separation of the compounds as they travel through the column.4. Detection: As the separated compounds exit the column, they pass through a detector that generates a signal proportional to the amount of each compound present. Common detectors used in GC include flame ionization detectors FID , thermal conductivity detectors TCD , and mass spectrometers MS .5. Data analysis: The detector generates a chromatogram, which is a graphical representation of the detector signal as a function of time. Each peak in the chromatogram corresponds to a specific compound, and the retention time of the peak can be used to identify the compound by comparing it to the retention times of known standards. The area under each peak is proportional to the concentration of the corresponding compound in the mixture. By using calibration curves obtained from analyzing known concentrations of the compounds, the concentration of each compound in the mixture can be determined.In summary, gas chromatography can be used to determine the composition and concentration of different organic compounds in a given mixture by separating the compounds based on their interactions with the stationary phase, detecting the separated compounds using a suitable detector, and analyzing the resulting chromatogram to identify and quantify the compounds.