I extracted DNA/RNA from FFPE tissue for the first time following the manufacturer's protocol (column-based), but some obstacles occurred:

1. Should i deparaffin twice if the sections still embedded? Whether xylene has impact on tissue samples and final yield?

2. How many section(s) of each block is necessary or proper?

3. According to the protocol: place the tube (containing tissue) in 37℃ for 10 min to evaporate ethanol completely. However, it still remains in tube. Should i elevate the temperature? If yes, which point is appropriate?