1. Ethanol precipitation can be used to separate DNA from unincorporated nucleotides. When working with radiolabeled probes, proper protection and waste disposal are required.

2. Add 0.5 volumes of 7.5 M ammonium acetate and 2 volumes of cold ethanol (-20 °C), vortex, centrifuge at 12,000 rpm for 30 minutes.

3. Remove supernatant, add 3 volumes cold 70% ethanol (-20 °C), centrifuge at 12,000 rpm for 10 minutes.

4. Remove supernatant, air dry, and resuspend the probe in a suitable buffer.