Abstract: Provided is an extraction column (1) including a first column (10) having an adsorbent layer (100) and a second column (20) detachably coupled to the first column (10) and filled with a trapping layer (200) containing zirconium oxide in a powder grain form. After a solution containing an organic halogen compound and an impurity has been added to the adsorbent layer (100), an aliphatic hydrocarbon solvent is supplied to and passes through the adsorbent layer (100) and the trapping layer (200) in this order. At this point, the impurity in the solution is treated in the adsorbent layer (100), and the organic halogen compound in the solution is dissolved in the aliphatic hydrocarbon solvent and passes through the adsorbent layer (100). Then, the organic halogen compound is trapped in the trapping layer (200). After passage of the aliphatic hydrocarbon solvent, an extraction solvent is supplied to the second column (20) separated from the first column (10).