Hi, Bioforumers:

I have a problem wanting your help. When i use the spectrophotometer to quantify the RNA products i extracted from plant, i found that the OD260/OD280 > 2.0. I checked it up in the references, but there are no discussions upon that. Would you please help me with that.

Thanks .

all the best!

hi
usually this ratio should be between 1.8 and 2 for good DNA quality. i've heard once that for DNA prep, a too high ratio is nefaste and then could be great to do an other phenol chlo.
For RNA, the intervall is quite larger. From 1.6 to more than two(2.3 is still ok). According to the principle of quantitation, a highly pure RNA should have a high ratio.
i don't know what your rna is for, but load part of it on a gel and see how it looks like. take again the OD and include the 260/230 ratio (salts and solvants).
if you want a true OD, it should be taken at 95° where secondary structures of rna are avoided. in fact, OD at room temperature is 10% less than 95°_OD. But assuming that all samples are treated same way, it's not a problem.

if you want to be sure, to an other phenol chlo and precipitate again. but if your ratio is up to 2.2 i don't think it's necessary.

I have exactly the same problem. I am also extracting RNA from plants (barley and pea). Did you find a solution? Does anyone have an idea to what causes the ratio to be higher than 2 and what to do about it?