Chapter 26: Q 26.7. (page 716)
Describe how the retention factor for a solute can be manipulated.
The retention factor for a solute can be manipulated by changing the temperature, stationary phase, and length of the column in gas chromatography.
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From the data in Problem 26-14, calculate for species C and D
(a) the resolution.
(b) the length of column necessary to separate the two species with a resolution of 2.5.
From the data in Problem 26-14, calculate for species B and C
(a) the resolution.
(b) the selectivity factor a.
(c) the length of column necessary to separate the two species with a resolution of .
(d) the time required to separate the two species on the column in part (c).
Describe a method for determining the number of plates in a column
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.
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)?
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