Hi Adriana,

What was the blood volume? Was it an RNA from total blood or serum/plasma? Which tubes did you use for blood sampling? How did you measure quantity and quality (Bioanalyzer, nanodrop, Qubit)?

Hi Juan

Thank for your help, I use 100 ul of total blood sample, lavander top tubes with EDTA, I did quantification with nanodrop 2000 and the quantity was ~ 4 ng/nl and the relation 260/280 and 260/230 < 1.6. The  blood samples are from patitents of Alzheimer and control. Thanks you very much again

Cordially,

Adriana.

Hi Adriana,

Clearly something went wrong. From the information provided, It is difficult to judge  but I would probably check the following:

1) Were buffers reconstituted correctly? (i.e. adequate volume of EthOH and concentration?)

2) Have you followed the protocol for Biological liquids in here?: http://www.zymoresearch.com/downloads/dl/file/id/467/r2050i.pdf

3) What is your final elution buffer and volume (i.e. 50 uL 0.1 mM EDTA pH 8.0)? Have you check RNA integrity on a Bioanalyzer RNA pico/nano chip? It might help to understand if the problem is also associated with degradation or it's simply due to deficient recovery.

4) Do you normally soak the columns on buffer prior loading your samples? 

In our experience, dealing with blood samples for RNA extraction is not too challenging but it requires some optimization before handling your samples (i.e. Best kit, best elution volume, RNA integrity, etc). I would therefore suggest to repeat this experiment but with a control sample, making sure that you follow the recommendations in the PDF in the link above. It should work fine. If you still experience problems with recovery/quality, I would suggest to use Qiagen products as they perform great with biofluids.

Hope this helps,

Juan