Look up: Percoll

1. Percoll
   Trademark for colloidal silica coated with polyvinylpyrrolidone that is used for density gradients. Inert and will form a good gradient rapidly when centrifuged. Useful for the separation of cells, viruses, and subcellular organelles.
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2. Percoll
   Trademark for colloidal silica coated with polyvinylpyrrolidone that is used for density gradients. Inert and will form a good gradient rapidly when centrifuged. Useful for the separation of cells, viruses and suB-cellular organelles. ... (18 Nov 1997) ...
   Found on http://www.mondofacto.com/facts/dictiona
   
   
3. Percoll
   `Percoll` was first formulated by Pertoft et al. as a tool for more efficient density separation. It is used for the isolation of cells, organelles, and/or viruses by density centrifugation. Percoll consists of colloidal silica particles of 15-30 nm diameter (23% w/w in water) which ...
   Found on http://en.wikipedia.org/wiki/Percoll