You have over dried your DNA and basically it is completely dehydrated.... do not dry any DNA more than 10 minutes after 70% ethanol wash... and that too dry it at room temp not in 37C incubator... I am not sure how bad did you dry the DNA, you can try to increase the volume, incubate at 37C and vortex if possible

Add TE tap it and keep it in 47 degreeC. This could happen due to handling error.

Dear friends

Thanks for your answers. I'll try your suggestions!

Best regards

Have a look at these other questions and the many helpful answers at RG:

https://www.researchgate.net/post/Why_is_DNA_not_dissolving?

https://www.researchgate.net/post/How_can_I_reduce_the_viscosity_of_extracted_genomic_DNA?

https://www.researchgate.net/post/Extremely_viscous_gDNA_after_ES_cell_lysis_protocol?

I did DNA extraction with that method many times. Dehydration could have played a role also. But it doesn't matter. I used such DNAs for usual PCR, Chip genotyping, Whole genome sequencing. They always work very well! DNA yield and concentration are very good, and for many downstream analyses you would need to dilute them. So it doesn't really matter if DNA is not solved completely.

Hi Najmeh

I agree with Hasan Rajabi, and also you can wait 2.5-3h at 37 0C after the addition of TE.

Hi Najmeh....

it is OK.....I used such DNA for PCR,They always work very well...also you can dissolved the precipitated DNA by incubation at 50C for 5 minutes, do not be afraid it is always work....

Dear friends

Many thanks for your suggestions.

Regards