Low TE Buffer

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• Low TE buffer has 10 times less EDTA than regular TE buffer. This prevents EDTA from interfering with any future interactions.

Materials

• Tris base
• EDTA (Ethylenediamine Tetraacetic Acid, Disodium Salt Dihydrate)
• HCL
• DI water
• stir bar

Equipment

• magnetic stir plate
• pH meter

Protocol

• 1. Add 800 ml deionized water to large erlenmeyer flask

• 2. Add appropriate amount of Tris Base and EDTA to create desired concentration

Concentration	Tris Base	EDTA	Final Molarity
20x low	24.22g	0.584g	0.2M Tris and 2mM EDTA
10X low	12.11g	0.292g	0.1M Tris and 1mM EDTA
1X low	1.211g	29.2mg	10mM Tris and 0.1mM EDTA

• 3. Add magnetic stir bar, mix for 5 mins at 300 rpm on magnetic stir plate

• 4. Set up stir plate and pH meter in fume hood and calibrate if needed.

  • Calibrate pH meter if it hasn’t been calibrated recently
  • Use 2-3 pH standards. Directions here
  • Keep pH meter in a liquid always! Do not let probe dry out!

• 5. Keep mixture mixing and slowly add HCl until pH is 8.0.

  • Keep mixture mixing on magnetic stir plate at 300rpm
  • Put the pH meter’s probe into mixture
  • Slowly add quantities of HCl, checking pH as you go, until pH is 8.0
    • As pH lowers, more HCl will be required to continue to lower it since pH is a log scale
    • Last time it took 10.5mL amount of HCl, I recommend doing 1000 uL increment amounts to start and then do less as you get closer to 8.0
    • If you go over, adjust back down with NaOH

• 6. Bring volume to 1L with DI water

• 7. Tranfer mixture into a long-term autoclave-safe storage container

• 8. Sterilize by autoclaving for 50 min with cap tightened to a single turn. Store.

Diluting

• Double check pH is 8.0 before and after diluting
• Make 1X from 20X:
  • Combine 1 part 20X to 19 parts DI water (ex. 50uL 20X TE + 950uL DI H20)