TBS, or Tris-buffered saline, is a common pH-stabilizing biological buffer due to its low toxicity. It is prepared by dissolving Tris and sodium chloride in water, then bringing down the pH using hydrochloric acid. Tris-HCl has a pKa of 8.07 at 25C and has a buffering capacity at pH 7 to 9. TBS buffer interacts favorably with antibodies and is commonly used in immunoassay and immunostaining procedures, such as in washing, blotting and diluting.