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The diagram below represents a gas chromatograph - VCE - SSCE Chemistry - Question 1 - 2002 - Paper 1
Question 1
The diagram below represents a gas chromatograph. a. Clearly identify, on the diagram, the mobile and stationary phases in the gas chromatograph shown and explain h... show full transcript
Worked Solution & Example Answer:The diagram below represents a gas chromatograph - VCE - SSCE Chemistry - Question 1 - 2002 - Paper 1
Step 1
Clearly identify, on the diagram, the mobile and stationary phases in the gas chromatograph shown and explain how gas chromatography is able to separate the components of a gaseous mixture.
Answer
In the gas chromatograph diagram, the mobile phase is represented by the nitrogen (N2) gas cylinder leading into the column. The stationary phase is typically the column lining, which is coated with a liquid stationary phase that interacts with the sample components.
Gas chromatography separates components based on their volatility and interaction with the stationary phase. As the gaseous mixture is carried by the mobile gas through the column, different components travel at different speeds due to varying degrees of adsorption to the stationary phase. More volatile components spend more time in the gas phase and travel faster through the column, while less volatile components adhere more to the stationary phase and take longer to pass through, leading to separation.
Step 2
How many peaks would you expect to see in the resulting chromatogram? Justify your result.
Answer
You would expect to see one peak in the chromatogram if the sample is pure Stanozolol. This is because a pure substance does not have multiple components to separate, and thus, it would produce a single identifiable peak corresponding to its retention time. The area under the peak can also provide information regarding the concentration of Stanozolol in the sample.
Step 3
If a sample of pure Stanozolol were available, how could it be used in the gas chromatograph to confirm the identity of the suspect sample?
Answer
If a sample of pure Stanozolol is available, it could be used as a reference standard in the gas chromatograph. By injecting both the pure sample and the suspect sample under the same conditions, one can compare the retention times and peak characteristics. If the retention time and the peak shape of the suspect sample matches that of the pure Stanozolol, this supports the identification of the suspect sample as Stanozolol.