Scott buffer
The Scott-buffer is a buffer solution which in the hematoxylin-eosin staining of biological tissues is used. It is distilled water with 0.2% (w / v) sodium hydrogen carbonate and 2% (w / v) magnesium sulfate .
With this staining procedure it is necessary after the hematoxylin staining to increase the pH value in the tissue from acidic to slightly basic, which causes a color change from red-brown to blue-violet ("blueing"). Very often this is accomplished simply by rinsing with tap water . However, the disadvantage of this method is that the pH value of the tap water can fluctuate, and the waterworks reserve the right to chlorinate the water if necessary. Chlorinated water is unsuitable for blueing and destroys the color. Therefore, in the interest of laboratory quality assurance, tap water is sometimes replaced by Scott's buffer solution.