TBST is mixture of Tris-Buffered Saline

Tris-Buffered Saline

Tris-buffered saline is a buffer used in some biochemical techniques to maintain the pH within a relatively narrow range. Tris has a slightly alkaline buffering capacity in the 7–9.2 range....

 and Tween 20

Tween 20

Polysorbate 20 is a polysorbate surfactant whose stability and relative non-toxicity allows it to be used as a detergent and emulsifier in a number of domestic, scientific, and pharmacological applications...

. It is a buffer

Buffer solution

A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It has the property that the pH of the solution changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a...

 used for washing nitrocellulose membrane in western blotting and microtiter plate wells in ELISA

ELISA

Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...

 assays.

Contents of TBS-Tween

The following is a sample recipe for TBST:

• 50 mM Tris
  Tris
  Tris is an abbreviation of the organic compound known as trisaminomethane, with the formula 3CNH2. Tris is extensively used in biochemistry and molecular biology. In biochemistry, tris is widely used as a component of buffer solutions, such as in TAE and TBE buffer, especially for solutions of...
  
  
• 150 mM NaCl
• 0.05% Tween 20

Adjust pH with HCl to pH 7.6

The simplest way to prepare a TBS-Tween solution is to use TBS-T tablets. They are formulated to give a ready to use TBST solution upon dissolution in 500 ml of deionized water.