In non-suppressed ion chromatography (IC), the conductivity detection sensitivity of anions is generally less than that of cations. This is due to the difference in the molar conductivities between analyte and eluting ions. On the one hand, anion IC often gives a second system peak due to the distribution of the conjugate acid of the eluting ion to the stationary phase, 1-3 in addition to the first system peak (water dip). In previous work, 4,5 we proved that the detection sensitivities of inorganic common anions eluted between the void and the second system peak are significantly increased by using an organic strong acid, such as 5-sulfoisophthalic acid, 5 as the eluent. This effect is based on the distribution of the undissociated strong acid (conjugate acid of the eluting ion) to the stationary phase hydrophobically, which is very different from another increase in sensitivity proposed by Gjerde and Fritz 6 using benzoic acid as the eluent, based on a sift of the dissociation equilibrium of a weak acid in the mobile phase.Although our proposed method is more practical because the separation window is relatively wide, i.e., the advent of the 2nd system peak can be delayed, there has been a weak point in that the peaks of the chloride and nitrite ions overlap when using a commercially available anion-exchange column. In order to solve this problem, another high-resolution column must be found.On the other hand, high-efficiency ion-exchange columns could be prepared by modifying a conventional octadecyl-silica (ODS) column with a highly hydrophobic ionic surfactant, which were applied to the separation of common anions. [7][8][9][10]