Hi An-Yu,

I'm not familiar with Geneaid's GENEzol TriRNA Pure kit or the FavorPrep RNA kit so I can't comment on those. However, I have had success with the Zymo Direct-Zol kit. A simple way to increase the concentration of your RNA sample is to ethanol precipitate--I like to add Glycoblue coprecipitant to help me visualize the pellet if my RNA amount is low. I've also had success in concentrating my RNA samples with Thermo's GeneJET RNA Cleanup and Concentration kit.

Additionally, it is worth noting that, as you mentioned, the cell count may be low. You might want to try extracting from more cells to get a higher yield.

Hi, Margaret

Thanks for the answer, i will this kit for future!!

You can reprecipitate you RNA and resuspend it in a smaller volume. Some loss and degradation is expected.