When you separate something, if the molecular weight is ＜1000D, choose silica of 60 Å, 70 Å.

If the molecular weight is ＜10000D, choose 100 Å, 150 Å, 200 Å, 300 Å. If the molecular weight is ＜50000D, choose 500 Å, 800 Å, 1000Å.