protein precipitation: organic ratio vs plasma volume

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

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Hello,

For usual plasma volumes (50-200 ul), the solvent:plasma ratio is often 3:1 (at least with acetonitrile). Now I have read here and there that if one uses lower plasma volumes, for instance 5 or 10 ul, a higher ratio should be used, typically 6:1 or 10:1. Do you know why? I wonder if this is related to differential precipitation efficiency or simply for allowing better recovery of the supernatant after centrifugation.

And I wonder another thing: if I would mix 15ul ACN on 5 ul plasma, then add 50 ul water without prior centrifugation, would proteins redissolve or their denaturation would prevent resolubilisation?

Thanks for your comments
A 2:1 ratio of organic to sample should work.
Don Shelly
LGC Standards
2 posts Page 1 of 1

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