(EN) Provided are a method and system for recovering an acidic gas whereby metal ions such as iron ion, a heavy metal ion, etc. in an amine absorbing solution can be quantified within a short period of time at a high accuracy and a factor which enhances the corrosive properties of the amine absorbing solution can be removed at an early stage. The method for recovering an acidic gas comprises a step for gas/liquid contacting a gas to be treated with an amine absorbing solution and thus allowing the absorbing solution to absorb an acidic gas to thereby remove the acidic gas from the gas to be treated, a step for diffusing the gas from the absorbing solution having absorbed the acidic gas to thereby regenerate the absorbing solution and, at the same time, recover the diffused gas, and an analysis step for calculating the iron ion and/or heavy metal ion concentrations in the absorbing solution, wherein the analysis step comprises: a step for controlling the pH of the collected absorbing solution until the ions are adsorbed to a chelate resin; a step for passing the absorbing solution through the resin and thus allowing the resin to adsorb the ions in the absorbing solution; a step for passing the regenerated acidic solution through the resin having adsorbed the ions and thus desorbing the ions and, at the same time, regenerating the resin to thereby give an ion-containing sample; and a step for quantifying the ions in the sample and calculating the concentrations of the ions in the collected absorbing solution on the basis of the quantification results.
