Chromatogram 1 was obtained by analysis of a sample of a mixture of two sugars, A and B, using high-performance liquid chromatography (HPLC). Chromatogram 2 was obtained by analysing another sample of the same mixture by HPLC under different conditions. Consider the following changes which could be made to the operating conditions for HPLC. I decreasing the pressure of the mobile phase II decreasing the temperature III using a less tightly packed column Which of the changes would be most likely to produce chromatogram 2? A. Only I B. I only C. III only D. I and II only

SSCE VCE Chemistry Components of Mixtures: Chromatogram 1 was obtained by a

Chromatogram 1 was obtained by analysis of a sample of a mixture of two sugars, A and B, using high-performance liquid chromatography (HPLC) - VCE - SSCE Chemistry - Question 5 - 2007 - Paper 1

Question 5

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Chromatogram 1 was obtained by analysis of a sample of a mixture of two sugars, A and B, using high-performance liquid chromatography (HPLC). Chromatogram 2 was obta... show full transcript

Worked Solution & Example Answer:Chromatogram 1 was obtained by analysis of a sample of a mixture of two sugars, A and B, using high-performance liquid chromatography (HPLC) - VCE - SSCE Chemistry - Question 5 - 2007 - Paper 1

Step 1

I decreasing the pressure of the mobile phase

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Answer

Decreasing the pressure of the mobile phase generally results in decreased flow rates, which can lead to broader peaks and less resolution. This change is not expected to reproduce the tighter and more defined peaks seen in chromatogram 2.

Step 2

II decreasing the temperature

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Answer

Decreasing the temperature can influence the interaction between the analytes and the stationary phase, often leading to increased retention times. This could explain a shift toward broader peaks, which is not consistent with the observed changes in chromatogram 2.

Step 3

III using a less tightly packed column

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Answer

Using a less tightly packed column would likely lead to increased Gaussian peaks and reduced resolution, making the separation less effective. This adjustment would align well with the differences exhibited in chromatogram 2.

Chromatogram 1 was obtained by analysis of a sample of a mixture of two sugars, A and B, using high-performance liquid chromatography (HPLC) - VCE - SSCE Chemistry - Question 5 - 2007 - Paper 1

Worked Solution & Example Answer:Chromatogram 1 was obtained by analysis of a sample of a mixture of two sugars, A and B, using high-performance liquid chromatography (HPLC) - VCE - SSCE Chemistry - Question 5 - 2007 - Paper 1

I decreasing the pressure of the mobile phase

II decreasing the temperature

III using a less tightly packed column

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