Tuesday, July 23, 2019

Column efficiency in chromatography

The efficiency of the packed column is articulated by the N (number of theoretical plates). N is a non-dimensional number and represents the kinetics of chromatographic retention mechanism. Efficiency, (N) relies on the physical properties of chromatographic medium with system dimensions and chromatography columns. Efficiency can be changed by altering the column length, particle size, or flow rate of the chromatographic system.
The higher the number of theoretical plates in a column, the higher the efficiency of it, and after that, the more resolution can achieve. The efficiency of the column can be empirically determined by using the equation below based on that region when an analyte is eluted from the column.
The number of theoretical plates (N), is given by N=5.54 (V1/W1/2)2
Where V1 is the retention volume of the peak, W1/2 is the peak width (volume) at half peak height.
The height equivalent to a theoretical plate (H) is recognized by H = L/N
Where L is the column length, N is the number of theoretical plates. Any parameter alters that increase column efficiency (N) will also increase peak resolution (Rs).
The most important part in column efficiency is the efficacy of the column packing and particle size. It is to pack an efficient column with the smallest particle size is the trickiest. This causes the particle size less than 10 microns are available commercially in pre-packed formats only. The limit of efficiency (theoretical Plate) is N > 2000. 


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