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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 ... 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 given diagram, the mobile phase is represented by the nitrogen () gas flowing through the system, while the stationary phase is the column inside the chromatograph. The mobile phase carries the gaseous sample through the column, where it interacts with the stationary phase.
Gas chromatography separates components based on their different affinities for the stationary phase. The time each component spends in the column, known as retention time, varies depending on how strongly it interacts with the stationary phase. Components that interact more strongly will take longer to pass through the column, allowing for effective separation.
Step 2
A pure substance was suspected of being the high molecular weight anabolic steroid Stanozolol. A sample of this substance was dissolved in a suitable pure solvent and injected into a gas chromatograph. How many peaks would you expect to see in the resulting chromatogram? Justify your result.
Answer
If Stanozolol is indeed a pure substance, we would expect to see one peak in the resulting chromatogram. This peak corresponds to the single compound being analyzed. The height and area of this peak can then be used to quantify the amount of Stanozolol present in the sample. Any additional peaks would indicate the presence of impurities or other substances.
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
To confirm the identity of the suspect sample, the pure Stanozolol can be injected into the gas chromatograph under the same conditions as the sample in question. By comparing the retention time of the peak from the pure Stanozolol with the retention time of the peak from the suspect sample, we can ascertain if they match. A match in retention times would suggest that the suspect sample contains Stanozolol, providing confirmation of its identity.