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Old 06-15-2016, 09:01 AM   #4
Location: Canada

Join Date: Jun 2013
Posts: 56

Hi again,

If you have already tried soaking the samples then I doubt that PBS would help you out.

If the problem is indeed guanidine-HCl or other chaotropic salts, I expect that those would be originating from the binding and perhaps the first wash buffers of the kits. I say this because RNAlater is essentially a saturated solution of Ammonium Sulfate along with 25 mM Sodium Citrate and 10 mM EDTA with a pH adjusted to ~5.2 []. I do not know why this would be that much different from ETOH but perhaps someone else might know.

I've mostly extracted RNAlater preserved leaf extracts but I have a colleague extracting from RNAlater preserved fish gill tissues so I'll post an update when they get some NanoDrop results.

All that said, you could try additional washes with the final buffer and an extra spin to dry out your spin columns to get rid of any salts. You could also try to clean up your spin column-eluted DNA with some ampure or similar beads but I have had little to no luck getting better nanodrop ratios with a secondary clean-up.

If you want to try another extraction method with a different mechanism of DNA precipitation, I have had good results with glycogen and polysaccharide rich plant and shellfish tissues using the Xin and Chen method:

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