A method refines a lubricant comprising a compound having a
perfluoropolyether structure via supercritical extraction. A lubricant is
refined using the method and a magnetic recording medium that utilizes
the refined lubricant. The refined lubricant exhibits excellent
lubrication performance and long term stability in the magnetic recording
medium. In one embodiment of the supercritical extraction, the lubricant
contacts an extracting medium of supercritical carbon dioxide under a
predetermined condition in a pressure vessel to remove ionic impurities
and perfluoropolyether compounds having a weak polarity terminal group
contained in the lubricant.