Chapter 26: Q 26.12. (page 716)
List the variables in chromatography that lead to zone separation
Variables in chromatography that lead to zone separation are
the temperature of the mobile phase, Length of the column, and Composition of the mobile phase.
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List the variables that lead to zone broadening in chromatography.
If VS and VM for the column in Problem 26-18 are 19.6 and , respectively, and a nonretained air peak appears after , calculate
(a) the retention factor for each compound.
(b) the distribution constant for each compound.
(c) the selectivity factor for methylcyclohexane and methylcyclohexene.
What variables are likely to affect the selectivity factor for a pair of analytes?
A chromatogram of a two-component mixture on a packed LC column is shown in the following figure. The flow rate was data-custom-editor="chemistry" .
(a) Find the times that components A and B spend in the stationary phase.
(b) Find the retention times for A and B.
(c) Determine the retention factors for the two components.
(d) Find the full widths of each peak and the full width at half-maximum values.
(e) Find the resolution of the two peaks.
(f) Find the average number of plates for the column.
(g) Find the average plate height.
(h) What column length would be needed to achieve a resolution of ?
(i) What time would be required to achieve the resolution in part (h)?
(j) Assume that the column length is fixed at role="math" localid="1649053810406" and the packing material is fixed. What measures could you take to increase the resolution to achieve baseline separation?
(k) Are there any measures you could use to achieve a better separation in a shorter time with the same column as in part (j)?
Describe the general elution problem.
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