Use the following magnified view of a two component separation to calculate teh
ID: 1061807 • Letter: U
Question
Use the following magnified view of a two component separation to calculate teh following values assuming a column length of 5cm and the dead time is 10 seconds
a) The retention fator for peaks A (the first peak)and B (the second peak)
b) the selectivity or separation of factor (?)
c) The plate count of the column
d) The height equivalent to the theoretical plate for each peak
e) The resolution of peaks A and B
f) Is this an acceptable resolution for quantitative analysis? If no, make a suggestion on how to improve resolution.
Signal 2.5 an .5 0.5 80 54 58 46 48 50 Time (sec)Explanation / Answer
a) retention factor = t- t0 / t0
RfA = tA - t0 / t0 = 50-10 / 10 = 4
RfB = tB - t0 / t0 = 53-10 / 10 = 4.3
b) Selectivity factor () = tB - t0 / tA - t0
= 1.075
c) Plate count / Number of theoretical plates
For Peak A)
NA = 16 (tA / Wb)1/2
NA = 16 ( 50/ 2.8)1/2
NA = 67.61
NB= 16 (tB / Wb)1/2
NB=16 (53 / 2.4)1/2
NB= 75.19
d) Height equivalent to theoretical plate
HA = L / N = 50 mm / NA = 50 / 67.61 = 0.739
HB = L / N = 50 mm / NB = 50 / 75.19 = 0.665
e) Resolution of peak A and B
Rs = 2 (tA - tB) / (WA + WB) = 2 (53-50)/(2.8+2.4) = 1.153
f) As this is less than 1.5 so it is not acceptable resolution for quantitative analysis
By decreasing the plate height and by increasing the plate number we can increase the resolution.
Other methods like pH will depend upon the nature of the compounds
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