Origins of band broadening in HPLC

H is the measure of the efficiency of the column (discussed above) the smaller the term the more efficient the column. 

B is rate of diffusion of the molecule in the liquid phase which contributes to peak broadening through diffusion either with or against the flow of mobile phase the contribution of this term is very small in liquid chromatography. Its contribution to band broadening decreases as flow rate increases and it only becomes significant at very low flow rates. 

is the resistance to mass transfer of a molecule in the stationary phase and is dependent on its diffusion coefficient in the stationary phase and upon the thickness of the stationary phase coated onto silica gel  

Resistance to mass transfer of a molecule within a particie of stationary phase. 

C is resistance to mass transfer brought about by the diameter and shape of the particles of stationary phase and the rate of diffusion of a molecule in the mobile phase. 

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