Composition comprising vinyl alcohol-based polymer, and method for separating vinyl alcohol-based polymer

A composition comprising:

• a vinyl alcohol polymer (A) that exhibits a retention time RT of a peak top of 22 min or more, as measured on reversed-phase partition gradient high-performance liquid chromatography with a water-ethanol eluent;
• and
• a compound (B), wherein the compound (B) is a compound represented by formula (1):
• wherein,
• in the formula (1), X represents an oxygen atom, a group represented by formula (2), or a group represented by formula (3);
• Y represents an atomic group having 1 to 10 carbon atoms;
• Z represents one selected from the group consisting of a carboxy group, a sulfo group, a phosphoric acid group, a salt thereof, and an anion thereof;
• and R1 represents an acyl group or a hydrocarbon group,
• in the formula (2) and the formula (3), R2, R3, and R4 each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an atomic bonding that bonds to Y;
• and * denotes an atomic bonding.