Buffer QG (Gel Purification Buffer)

Final Buffer Concentration: 

  • 5.5 M Guanidinium thiocyanate (GuSCN)

  • 20 mM Tris HCl (pH 6.6)

Equipment & Consumables

  • PPE: Gloves, Lab Coat and Goggles (at least!)

  • Micropipettes and Tips

  • Weighing Scale (accurate to to 0.01g)

    • Weigh boats (or folded paper)

  • Filters & Syringes OR Autoclave

  • Optional: Heated/Stirring Platform - Highly Recommended for this buffer.

  • pH Meter (recently calibrated)

  • Graduated Beaker (50 ml graduation, but ensure it is at least 1 L to avoid spills)

  • Measuring Cylinder

  • 4°C Refrigerator

  • ddH20 (MilliQ or RO)

  • 32.494 g GuSCN - Seriously nasty stuff! Be extremely cautious when handling, do not inhale!

  • 1.211 g Tris Base

  • Autoclave or sterile syringe filters

Protocol:

For mIxing 50 ml of QG Buffer:

First mix 10 ml 1M Buffer Tris-Cl Solution (pH 6.6)

  1. Dissolve 1.211 g of Tris Base in 5 ml of water.

  2. Add dilute HCl to balance the pH to 6.6.

  3. Make up to 10 ml with dH2O.

  4. Autoclave or filter sterilise (may not be necessary, since GuSCN is so toxic. However autoclaving will allow you to store it for potential use later).

Next dissolve the GuSCN on a heater stirrer and add your autoclaved Tris-Cl buffer:

  1. Equip all of your PPE.

  2. Set up 20 ml of sterile water on a heated stirring platform set to no more than 60°C.

    • This dissolution is extremely endothermic and will take forever without heating. That said, you don’t want to boil anything.

    • Stir slowly, don’t let any escape the beaker.

  3. Slowly add 32.494g of GuSCN to the water, allow time for it to dissolve completely. This may take up to 10 minutes depending on heating.

  4. Add 1 ml of your 1M Tris-Cl buffer.

  5. Make up the volume to 50 ml using sterile water and the graduation on the beaker.

  6. Store at 4°C.

    • This buffer will last several months before a white precipitate forms. This tends to indicate that it is borked, but perhaps you could try redissolving the precipitate and seeing if it works?

    • Take extreme care to appropriately dispose of this buffer, do not let it anywhere near bleach or bleach waste.

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