以常规的抑制型离子色谱仪为基础，在抑制器之后和紫外检测器之前，依次串联两根自制的离子置换柱，第一根为Li⁺型阳离子置换柱，第二根为IO₃^-型阴离子置换柱。IC测定中用Dionex IonPac AS18阴离子交换柱为分离柱，以30 mmol·L^-1氢氧化钠溶液为流动相。在测定亚氯酸钠的纯度及其杂质阴离子含量时，样品溶液（0.100 0 g样品溶于水中，定容至50.0 mL，分取部分溶液定量稀释100倍）在经过离子置换柱的过程中，亚氯酸根及其他待测阴离子均被定量地置换成同一的碘酸根离子，并通过紫外检测器，在波长210 nm处予以测定。结果表明：亚氯酸根及其他4种杂质离子的浓度在一定范围内与其对应的峰面积呈线性关系，检出限（3S/N）在6.09~19.66 μg·L^-1之间。按标准加入法进行回收试验，回收率在96.0%~101%之间，测定值的相对标准偏差（n=6）在1.1%~3.0%之间。

As an attachment to the conventional suppression ion chromatograph, two self-prepared ion replacement columns were installed in series between the suppressor and the UV-detector successively. The former is a cation replacement column of Li⁺-type and the latter is an anion replacement column of IO₃^--type. Dionex IonPac AS 18 anion exchange column was used for separation in IC analysis, and 30 mmol·L^-1 NaOH solution was used as mobile phase. In the determination of purity of sodium chlorite and its impurityanions, when the sample solution (prepared by dissolving 0.100 0 g of the sample in water, making its volume to 50.0 mL, and still-further by diluting an aliquot of the solution 100 times quantitatively) was separated through the anion-exchange column and then passed through the 2 ion-replacement columns, the anions, i.e., ClO₂^- and the other 4 anions, were all replaced to the same anion of IO₃^-, and determined at the wavelength of 210 nm by the UV-detector. As shown by the results, linear relationships between values of peak area and concentration of chlorite and other impurity ions were obtained in definite ranges, with detection limits (3S/N) in the range of 6.09-19.66 μg·L^-1. Test for recovery was made by standard addition method and the values of recovery were found in the range of 96.0%-101%, with RSDs (n=6) ranged from 1.1% to 3.0%.