Chapter 23: Q42P (page 631)

23-42. A separation of $2.5 mg$ of an unknown mixture has been optimized on a column of length L and diameter d .
(a) Explain why you might not achieve the same resolution if the $2.5 mg$ of unknown mixture were injected in twice the injection volume.
(b) Explain why you might not achieve the same resolution if $5.0 mg$ of unknown mixture were injected in the original injection volume.

Short Answer

Expert verified

(a) We might not get the same resolution since a larger injected band may result in wider eluted peaks (wider peaks = worse separation).’

(b) We may not achieve the same resolution because higher sample concentrations may cause the column to become overloaded (as in the previous task). (You can see the changes induced by an overload of the column in the preceding task).

Step by step solution

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The separation of $2.5 mg$ an unknown combination has been optimized on a column of length (L) and diameter (D) in this task (d).

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a) We'll explain why injecting $2.5 mg$ of unknown combination in twice the injection volume could not result in the same resolution.

We might not get the same resolution since a larger injected band may result in wider eluted peaks (wider peaks = worse separation).

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b) We'll explain why injecting 5.0 mg of unknown combination in the initial injection volume might not yield the same resolution.

We may not achieve the same resolution because higher sample concentrations may cause the column to become overloaded (as in the previous task). (You can see the changes induced by an overload of the column in the preceding task).