TE+Tween

10 mM Tris–HCl + 1 mM EDTA + 0.05% Tween 20, pH 8.0 @ 25 °C

Purpose

• Tris buffers, with their pH adjusted by HCl, are often used to store DNA.
• EDTA chelates divalent cations like magnesium, which can contribute to DNA degradation.
• Tween 20 is a non-ionic detergent that reduces adsorption of DNA to plastics and improves pipetting accuracy.
• This buffer is useful for long-term storage of DNA to be used in quantitative assays, although the EDTA must be taken into consideration for any enzymatic reaction that relies on a divalent cation.

Recipe

Final concentrations

Tris base	10 mM
disodium EDTA	1 mM
Tween 20	0.05% (v/v)
HCl	3.72 mM

Preparing 50 mL of 1X working solution

water	48.564 mL
Tris base, 1 M	0.500 mL
disodium EDTA, 0.1 M	0.500 mL
Tween 20, 10% (v/v)	0.250 mL
HCl, 1 N	0.186 mL

Preparing 50 mL of 10X concentrate

water	35.64 mL
Tris base, 1 M	5.00 mL
Disodium EDTA, 0.1 M	5.00 mL
Tween 20, 10% (v/v)	2.50 mL
HCl, 1 N	1.86 mL

Notes

• HCl titration was calculated with the Python package ionize 0.8.0.
• pH is temperature-dependent and this dependency is especially strong for Tris, so pH indicators may show a noticeably higher pH than 8.0 at temperatures lower than 25 °C.