Modified from a protocol by Travis Glenn at Univ. South Carolina

Do not use for PCR products less than 300bp.

  1. Set heatblock/water bath to 37C.
  2. Run 2 uL of PCR product on a minigel to ensure the reaction worked.
  3. Add 50 uL (for 50uL PCR reactions) of PEG to a 0.7 mL tube. Add the remainder of the PCR product and mix by pipetting up & down.
  4. Incubate at 37C for 15 minutes.
  5. Centrifuge (max speed) 15 minutes.
  6. Pipette off the liquid and discard it. Careful–the pellet probably won’t be visible.
  7. Add 125 uL ice cold 80% EtOH
  8. Centrifuge 2 minutes.
  9. Pipette off the liquid and discard it.
  10. Repeat steps 7-9.
  11. Dry 15-30 minutes in a speedvac if available–otherwise air-dry, spinning briefly every few minutes to ensure the final droplet doesn’t “climb” the tube as it evaporates). There should be no trace of liquid or EtOH odor.
  12. Spin briefly to ensure DNA is at the bottom of the tube.
  13. Add 25uL TE buffer (10mM Tris, 0.1mM EDTA recipe). Mix by pipetting.
  14. Incubate at 37C for 5 minutes.
  15. Turn off heatblock/waterbath
  16. Quantify on Nanodrop.

Recipes

PEG for purification of PCR products

20% PEG, 2.5 M NaCl

  • For 50mL (enough for ~1000 PCR reactions) mix the following in a 100mL Pyrex bottle:
    • 10.0 g PolyEthylene Glycol 8000 (MW = 6000 - 8000 is fine)
    • 7.3 g NaCl
    • ddH2O up to ~45 mL
  • Stir with magnetic rod on lowest heat. PEG may not completely dissolve depending on how much water you’ve added, but after 20-30 minutes, fill with ddH2O up to 50 mL and mix until completely dissolved.
  • Store in the refrigerator.

Note- This recipe is good for PCR products larger than 300bp. Increasing PEG or NaCl concentrations will allow smaller products.