Question

Two isotopic compounds are produced in the synthesis of a new therapeutic drug, which must be separated by repeated chromatography cycles. In each cycle, the solution containing both compounds passes through a chromatography column with a length L = 45.0 cm containing N theoretical plates. The unadjusted relative retention is y = 1.098. Calculate the number of theoretical plates, N. in the column of length L. The observed resolution is 1.82 after 14 cycles. plates Calculate the height of an individual plate in micrometers. Estimate the resolution in 7 cycles, resolution:

Answer 1

L = 45.0 cm

γ = 1.098

After 14 cycles, observed resolution =1.82

Step 1:

To calculate the number of theoretical plates N in the column, use the following expression:

Resolution = √N/4 (γ - 1)

1.82 = √12 x N/4 (1.098 - 1)

N = 460 plates

Step 2:

To calculate the plate height of one theoretical plates in this column, where there are 460 theoretical plates:

N = L/H

rearrange the formula as:

H = L/N

H = 45 cm / 460

H = 9.783 x 10^-2 cm

H = 9.783 x 10^-2 cm x 10⁴ um/1 cm

H = 978.26 um

Step 3:

For the last part of the problem: Estimate the resolution in 7 cycles.

resolution in 7 cycles/resolution in 14 cycles =√ (# cycles 1 /# cycles 2)

resolution in 7 cycles/1.82 =√ (7 /14)

resolution in 7 cycles = 1.287