| 摘要 |
An impurity derived from a high-molecular-weight polyethylene glycol compound is removed from a high-molecular-weight polyethylene glycol compound whose total average number of moles of ethylene oxide units added in the molecule is 220 to 4500. In a state where the high-molecular-weight polyethylene glycol compound is dissolved in at least one of water and an organic solvent selected from aromatic hydrocarbon solvents having 8 or less carbon atoms in total and ester compound solvents having 5 or less carbon atoms in total, the water and the organic solvent are mixed. The resulting mixture was separated into an organic layer and an aqueous layer, and the organic layer is separated from the aqueous layer.
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