Consider the chromatogram of deuterated benzenes in Box 24-1. (a) Unretained thiourea

Chapter 24, Problem 24-16

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Consider the chromatogram of deuterated benzenes in Box 24-1. (a) Unretained thiourea, is eluted in 41.7 min. Find the linear velocity ux (mm/s). (b) Find the retention factor k for C6D6. (c) Find the plate number N and plate height for C6D6. (d) Assuming that the peak widths for C6H5D and C6H6 are the same as that of C6D6, find the resolution of C6H5D and C6H6. (e) Retention times for C6H5D and C6H6 are 193.3 and 194.3 min, respectively. Find the relative retention () and unadjusted relative retention () between C6H5D and C6H6. (f) If we just increased the column length to increase N, what value of N and what column length would be required for a resolution of 1.000? (g) Without increasing the length of the column, and without changing the stationary phase, how might you improve the resolution? (h) When the solvent was changed from CH3CN/H2O (30:70 vol/vol) to CH3CN/CH3OH/H2O (10:5:85), the unadjusted relative retention changed from 1.0052 to 1.0083. If the plate number were unchanged, what would be the resolution?