What is the source of RNA? You could use acid phenol to further purify the RNA. The gel looks fine, however make sure you use RNAse free set up, and do not overrun it, because heating can lead to RNA degradation.

dear Mr Rozhkov,

thanks for reply. I have extracted from cell line.

For RNA isolation for NGS, we use the QIAamp Viral RNA Mini Kit (Qiagen) with a Qiavac vacuum manifold to increase throughput by pooling several tubes containing the same sample together, followed by DNAse Turbo (Ambion) to clear DNA contamination from RNA samples.

However, if the sample has contaminants that affect downstream enzymatic reactions, additional purification steps such as a filter-based spin column repurification may help in the removal of contaminants and/or concentration of the sample.

Please find in the following link a list of different source of inhibitors and methods to minimize them: https://support.illumina.com/bulletins/2016/05/dnarna-isolation-considerations-when-using-truseq-library-prep-kits.html