The Relationship between Dispersion in a Packed Column to Solute Molecular Weight

The Relationship between Dispersion in a Packed Column to Solute Molecular Weight 

at high linear velocities, the longitudinal diffusion term will become insignificant and, equally important, the resistance to mass transfer term that incorporates the inverse function of diffusivity will become large, thus improving the precision of measurement. 

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In order to relate the value of (H) to the solute diffusivity and, consequently, to the molecular weight according to equation (11), certain preliminary calculations are necessary. It has already been demonstrated in the previous chapter (page 303) that the dynamic dead volume and capacity ratio must be used in dispersion studies but, for equation (11) to be utilized, the value of the multipath term (2Xdp) must also be 

Interactions in the stationary phase employing a porous stationary phase or support must also involve the mobile phase trapped in a static form inside the pores. It follows that the diffusivity of the solute in the stationary phase (Ds) will be similar to that in the mobile phase (Dm). Thus, to a first approximation, it can be assumed that Ds = coDm, where (co) is a constant probably close to unity. Thus, equation 

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