Effect of Electroosmotic Flow on the Electrical Conductivity of Packed Capillary Columns

The electrical conductivity of a packed capillary column is primarily a function of column porosity and tortuosity; therefore it can be used for column characterization in capillary electrochromatography (CEC). However, a deviation from this functionality may occur due to electroosmotic flow, which contributes to the observed conductivity by transporting excess charges in double layers. On the basis of Rice and Whitehead's theory combined with a capillary tube model, we have shown that the electroosmotic conductivity increases with the ζ potential but decreases with the particle diameter and electrolyte concentration. Under typical conditions employed in current CEC, the electroosmotic conductivity accounts for less than 5% of the bulk conductivity of the same electrolyte and indeed can be neglected for practical purposes.