1. Separations

2. Column chromatography
Multiple extraction event
qn = (V1/((V1+KV2)n
K = partition coefficient = [S2]/[S1]
Column Chromatography
K = [S]s/[S]m
n is analogous to N – the number of theoretical plates
N depends on separation efficiency (H) and length of the column (L)

3. Characterizing the Retention Parameters for a given Application
Retention coefficient or capacity factor
k’ = (tr-tm)/tm

4. Selectivity factor Selectivity factor for A and B– a
..a = k’B/k’A = [(tr)B-tm] / [(tr)A-tm]
Depends on properties of A and B and experimental conditions
Independent of flow rate
Good way to evaluate performance of column

5. Parameters of Column Plate Height – H = s2/L = L/N For Gaussian peak
= LW / 4tr
H = LW2 / 16t2r
N = 16(tr/W)2

6. Separation of two components
Resolution
R = [(tr)B – (tr)A] / Wave
R = N1/2/4 [(a-1)/a] [k’B/(1+k’B)]
Can adjust resolution by changing N, a, and k’B.
Adjusting a and k’B
Mobile phases, temperature, stationary phases, additives
Adjusting N
Changing column (length or diameter)

7. Column Efficiency - H Van Deempter Equation
H = A + B/v + Cv
There is a optimal linear flow rate for a given column
GC is generally more efficient than HPLC due to practicality of longer columns