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 electro osmotic flow, which contributes to the observed conductivity by transp orting excess charges in double layers. On the basis of Rice and White head's theory combined with a capillary tube model, we have shown that the electroosmotic conductivity increases with the zeta potential but decreases with the particle diameter and electrolyte concentration. U nder typical conditions employed in current CEC, the electroosmotic co nductivity accounts for less than 5% of the bulk conductivity of the s ame electrolyte and indeed can be neglected for practical purposes.