A method to refine a lubricant on a magnetic recording medium includes a compound
A including a perfluoropolyether molecular structure having two hydroxyl groups
at each of two ends and a compound B including the perfluoropolyether molecular
structure having one hydroxyl group at each of two ends. The method includes putting
the lubricant into a pressure vessel set at a pressure and a temperature and removing
the compound B dissolved in an extracting medium of a supercritical carbon dioxide
fluid that flows at a predetermined rate through the pressure vessel held at a
predetermined temperature and at a predetermined pressure. The method performs
recovering the compound A dissolved in the extracting medium that flows through
the pressure vessel held at the predetermined pressure and at a temperature lower
than the predetermined temperature or at the predetermined temperature and at a
pressure higher than the predetermined pressure.
