“…According to different research groups, the parameters of the commonly used centrifugation procedure can be changed from 20 min at 2000 rpm [48,50,61], 6000 rpm [42] or 8000 rpm [62] to 10 min at 16 000 rpm [63]. Most of the time the product is then dispersed in another solvent such as water [6,42,[62][63][64], ethanol [42,50] or methanol [65] to be washed a second time. Filtration has also been described to further purify the product, either by filtering through a polycarbonate membrane with 0.8 µm pore size [51,58] or a glass filter with mean pore size of 5-40 µm [66,67].…”