In what way you are talking about the quality of GO?

As GO has several functional groups attached on it therefore,there would be no big change for functional groups. I feel there might be some other ions on the sheets those are making it more hydrophilic in pH range towards 7-8.

Dear Jw Heo ,

Generally, it does not effect on the quality of GO. Anyway, it's also dependence upon the environment of preserving/ storing.

Regards,

Dear Jw Heo,

It's ok no problem to take GO in Di water even longer time almost for a week, the DI water has no effect on the properties of GO.

Thanks & Regards

Unfortunately, water is not an innocent solvent/dispersing medium for GO. 3 days may be ok but a long time may make it acidic ... check out this important article:

Article Graphene Oxide. Origin of Acidity, Its Instability in Water,...