I am measuring nuclear total RNA from mouse embryonic cortical tissues. I have done the bioanalyzer and for all the samples, it shows the rRNA ratio from 3.7 to 5.0, which is way beyond the theoretically possible value(2.6). My gut feeling tells, the RNA is not degraded (as 28s rRNA peak is intact, and there are no smears on the lower sized rna), but why would it be the case? Any suggestion would be highly appreciated!

Thanks again in advance!