Gas chromatography GC is an analytical technique used to separate, identify, and quantify the components of a mixture of volatile compounds. It can be used to determine the composition of a mixture of two unknown compounds by following these steps:1. Sample preparation: First, prepare the sample by dissolving it in a suitable solvent. The sample should be in a small and concentrated volume to ensure proper injection and separation.2. Sample injection: Inject the prepared sample into the gas chromatograph using a microsyringe or an automatic injector. The sample is introduced into the injection port, where it is vaporized and mixed with the carrier gas usually helium or nitrogen .3. Separation: The vaporized sample is carried through a column packed with a stationary phase a solid or liquid material by the carrier gas. The stationary phase selectively retains the components of the mixture based on their chemical properties, such as polarity and molecular weight. The components with a higher affinity for the stationary phase will move more slowly through the column, while those with a lower affinity will move more quickly. This results in the separation of the components based on their retention times.4. Detection: As the separated components exit the column, they pass through a detector that measures their presence and relative abundance. 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's response as a function of time. The chromatogram displays peaks corresponding to the separated components, with the retention time on the x-axis and the detector's response on the y-axis. The area under each peak is proportional to the amount of the component in the sample.6. Identification and quantification: To identify the unknown compounds, compare their retention times and/or mass spectra if using a mass spectrometer with those of known reference compounds. This can be done using a library of reference spectra or by running standards alongside the unknown sample. Once the compounds are identified, their relative amounts can be determined by comparing the peak areas or peak heights in the chromatogram.In summary, gas chromatography can be used to determine the composition of a mixture of two unknown compounds by separating them based on their chemical properties, detecting their presence and relative abundance, and comparing their retention times and/or mass spectra with those of known reference compounds.