Determination of ultra low content of carbon in iron by ion-chromatography

A study on the determination of ultra low content of carbon was made by using ion-chromatography, coupled with the combustion method in oxygen gas stream. The considerable increase in the variation of conductivity with the content of carbonate ion was observed because of the high ionic conductivity of OH^- in the NaOH eluent. The Na⁺ (OH^-) ion could be removed by a cation exchange column according to the reaction:R-H⁺+NaOH→R-Na⁺+H₂O. Therefore, carbonate ions in NaOH absorbent, which absorbed CO₂ gas produced by the reaction of carbon in metal with oxygen gas, could be concentrated on the concentration column. It was found that 1.67 mass ppm of carbon in pure iron sample was determined within the accuracy of 0.24 mass ppm of standard deviation.