Gas chromatography GC is a powerful analytical technique that can be used to analyze the composition of complex mixtures, such as hydrocarbons in a gasoline sample. It works by separating the components of the mixture based on their volatility and affinity for the stationary phase in the chromatography column. Here's a step-by-step process on how GC can be used to determine the percentages of each component present in a gasoline sample:1. Sample preparation: First, a small amount of the gasoline sample is prepared for injection into the gas chromatograph. This may involve diluting the sample with a suitable solvent to ensure that the concentration of the components is within the detection range of the instrument.2. Injection: The prepared sample is injected into the gas chromatograph, where it is vaporized and mixed with an inert carrier gas, such as helium or nitrogen. The carrier gas transports the vaporized sample through the chromatography column.3. Separation: The chromatography column is packed with a stationary phase, which is typically a high-boiling-point liquid coated onto an inert solid support. As the vaporized sample moves through the column, the components of the mixture interact with the stationary phase to varying degrees. 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 differential migration results in the separation of the components based on their volatility and affinity for the stationary phase.4. Detection: As the separated components exit the column, they pass through a detector that measures their concentration. Common detectors used in GC analysis of hydrocarbons include flame ionization detectors FID and mass spectrometers MS . These detectors generate a signal proportional to the concentration of each component as it elutes from the column.5. Data analysis: The detector generates a chromatogram, which is a graphical representation of the signal intensity as a function of time. Each peak in the chromatogram corresponds to a specific component in the mixture. The retention time of each peak can be used to identify the component, while the area under the peak is proportional to the concentration of the component in the sample.6. Quantification: By comparing the peak areas of the components in the gasoline sample to those of known standards, the percentages of each component present in the mixture can be determined. This is typically done using calibration curves, which are generated by analyzing a series of standard mixtures with known concentrations of the components of interest.In summary, gas chromatography can be used to analyze the composition of a complex mixture of hydrocarbons in a gasoline sample by separating the components based on their volatility and affinity for the stationary phase, detecting their concentrations using a suitable detector, and quantifying their percentages using calibration curves.