The retention time (tr) and peak width (w) for compounds A and B are given after chromatographic separation using five different experimental parameters. Which chromatographic separations achieved a resolution that is desirable for quantitative analysis?

a. Separation 1: compound A: t; = 13.0 min; w = 5.0 min compound B: t; = 17.0 min; w = 6.5 min

b. Separation 3: compound A: tr = 14.0 min; w = 4.0 min

c. Separation 2: compound A: t; = 10.0 min; w = 3.0 min compound B: t; = 19.0 min; w = 3.0 min

d. Separation 4: compound A: tr = 11.0 min; w = 2.0 min compound B: tr = 16.0 min; w = 5.0 min compound B: tr = 15.0 min; w = 3.0 min

e. Separation 5: compound A: tr = 9.0 min; w = 2.5 min compound B: t; = 13.0 min; w = 4.5 min

Separation 2 has the highest resolution value which is 3, it is therefore the most desirable.

Explanation:

Note that in the given separations, the values for compound B which are missing in separation 3 were erroneously put in separation 4. These are the correct values for separations:

a. Separation 1: compound A: t; = 13.0 min; w = 5.0 min compound B: t; = 17.0 min; w = 6.5 min

b. Separation 3: compound A: tr = 14.0 min; w = 4.0 min compound B: tr = 16.0 min; w = 5.0 min

c. Separation 2: compound A: t; = 10.0 min; w = 3.0 min compound B: t; = 19.0 min; w = 3.0 min

d. Separation 4: compound A: tr = 11.0 min; w = 2.0 min compound B: tr = 15.0 min; w = 3.0 min

e. Separation 5: compound A: tr = 9.0 min; w = 2.5 min compound B: t; = 13.0 min; w = 4.5 min

Determination of chromatographic separation that achieved a resolution that is desirable for quantitative analysis

In chromatography, the formula for Resolution (R) = 2 (tR (B) - tR (A)) / (WB + W A)

For separation 1 : Resolution (R) = 2 (17.0 min - 13.0 min) / (6.5min + 5.0min) = 0.695

For separation 2 : Resolution (R) = 2 (19.0 min - 10.0 min) / (3.0min + 3.0min) = 3

For separation 3 : Resolution (R) = 2 (16.0 min - 14.0 min) / (5.0min + 4.0min) = 0.444

For separation 4 : Resolution (R) = 2 (15.0 min - 11.0 min) / (3.0min + 2.0min)

= 1.6

For separation 5 : Resolution (R) = 2 (13.0 min - 9.0 min) / (4.5min + 2.5min)

= 1.14

A chromatographic separation with a higher resolution is desirable for quantitative analysis. Since separation 2 has the highest resolution value which is 3, it is therefore the most desirable.