Why is there RNA in the DNA eluate when using the AllPrep DNA Mini Spin Column?
FAQ ID -1044

When using the AllPrep DNA/RNA Mini Kit, an acidic sample may reduce the pH of the Buffer RLT Plus lysate, which can result in RNA binding to the DNA column. It might be beneficial to adjust the pH of the lysate. However, diluting the lysate will change the salt concentration required for DNA binding, and may therefore lead to suboptimal extraction conditions.