Bio-Rad PureZOL™ RNA Isolation Reagent - Manual (Page 13)

8. Centrifuge at 12,000 x g for 10 minutes at 4°C.
9. The RNA will appear as a white pellet on the side and
bottom of the tube. Carefully discard the supernatant.
10.To wash the RNA pellet, add 1 ml of 75% ethanol for every
1 ml of PureZOL used in step 1.
At this point, the sample can be stored in ethanol at 4°C for at
least 1 week or at -20°C for at least 1 year.
11.Vortex the sample and then centrifuge at 7,500 x g (max)
for 5 minutes at 4°C. Carefully discard the supernatant.
12.Air-dry the RNA pellet for about 5 minutes. Do not let the
RNA pellet dry completely since this will decrease solubility.
Note: Do not use centrifugation by vacuum (Speed Vac).
13.Resuspend the pellet in the appropriate volume of RNase-
free water (DEPC-treated water). Pipet up and down a few
times to completely resuspend the pellet. It may be necessary
to incubate at 55–60°C for 10 minutes to completely dissolve
the RNA pellet.
Note: We recommend subsequent cleanup of the RNA using
an Aurum total RNA mini kit (732-6820) to remove any phenol
or other contaminants that may have coprecipitated with the
RNA. See section 8 for ordering information.
14.The extracted RNA can be used immediately in downstream
applications. Alternatively, the RNA sample can be aliquoted
and stored at –20°C for 1 month or at –70°C for 1 year. Avoid
freeze-thaw cycles.
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