Tris



Tris is a common buffering agent and is short for tris[hydroxymethyl]aminomethane (C4H11NO3, 2-Amino-2-hydroxymethyl-propane-1,3-diol).


 * The formula weight is 121.14
 * The pKa of Tris is 8.3
 * dpKa/dT is -.028
 * A buffer at pH 6.8 at 25&deg;C will have a pH of 6.46 at 37&deg;C
 * Note that adding HCl during titration will affect the temperature of the solution
 * Dilution by a factor of 10 will reduce the pH by 0.1 pH units.

Preparing a 1M Tris, pH 7.4 solution, from biologicalworld
(Be careful not to inhale the HCl.)
 * Weigh 121.1 g Tris in 700 ml double distilled water
 * Do not start with too much water; otherwise, the volume after pHing may be too great
 * Start stirring, and then check the pH
 * With a 3M HCl solution, start to pH the solution such that the pH reaches 7.4
 * Add with double distilled water up to 1L
 * Filter or autoclave if necessary
 * May be better to store at 4 degrees C
 * Dilute to appropriate concentration for use in biochemistry or molecular biology experiments. 20 mM or 50 mM Tris, pH 7.4 solutions are common.

Stability

 * 18 months for Tris-HCl buffer according to this data sheet
 * 2 years for Tris-EDTA according to this data sheet