Abstract: OBJECTIVE To determine sodium content in oligonucleotide bulk pharmaceuticals by ion-chromatography and atomic absorption spectrophotometry. To evaluate the degree of agreement between measurements. METHODS Ion chromatography (IC) was carried out by using an Ion-pac CS12 column (4 mm×250 mm) with methanesulfonic acid as the mobile phase, suppressed conductivity detector, on Dionex ICS 900. The results was compared with atomic absorption spectrophotometry (AAS) method provided by national standard. By using paired t test and Bland-Sltman method to estimate consistency of two methods. RESULTS The two method results showed that the precision were 2.0% and 0.7%, the repeatability were 2.0% and 7.96%, the analytical recovery were 99.6% and 89.8% for ion-chromatography and atomic absorption spectrophotometry, respectively. The mean difference was -0.0136% with 95% confidence. CONCLUSION There is no significant difference compared with the national standard method-AAS. Moreover, the ion-chromatography method had demonstrated its superiority in repeatability and analytical recovery.