Tris-buffered saline

Tris-buffered saline (abbreviated TBS) is a buffer used in some biochemical techniques to maintain the pH within a relatively narrow range. Tris (with HCl) has a slightly alkaline buffering capacity in the 7–9.2 range.  Tris has a pK_a of 8.06 at 25 °C. The pK_a declines approximately 0.03 units per degree Celsius rise in temperature. This can lead to relatively dramatic pH shifts when there are shifts in solution temperature.