Tris+Tween

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

Purpose

• Tris buffers, with their pH adjusted by HCl, are often used to store DNA.
• Tween 20 is a non-ionic detergent that reduces adsorption of DNA to plastics and improves pipetting accuracy.
• This buffer is recommended (e.g. in the Kapa Library Quantification Kits) for diluting DNA before enzymatic reactions like qPCR, because unlike TE it does not contain EDTA, which could interfere with those reactions.

Recipe

Final concentrations

Tris base	10 mM
Tween 20	0.05% (v/v)
HCl	5.63 mM

Preparing 50 mL of 1X working solution

water	48.9685 mL
Tris base, 1 M	0.5000 mL
Tween 20, 10% (v/v)	0.2500 mL
HCl, 1 N	0.2815 mL

Preparing 50 mL of 10X concentrate

water	39.685 mL
Tris base, 1 M	5.000 mL
Tween 20, 10% (v/v)	2.500 mL
HCl, 1 N	2.815 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.