pH 7.4, 1 M. Tris hydrochloride has been used as a component of extraction buffer e.g. phenol extraction of DNA or RNA; and as a component of separating and stacking gels in the characterization of in vitro translation products by SDS-PAGE. The pH values of Tris buffer solutions are temperature and concentration-dependent. Between 5 °C and 25 °C, the pH value increases an average of 0.03 pH units for each °C decrease in temperature. As the buffer temperature increases from 25 °C to 37 °C, the pH value decreases an average of 0.025 pH units per °C. Increasing the concentration of Tris from 0.05 M to 0.5M will increase the pH value by about 0.05 units. Decreasing the concentration from 0.05 M to 0.005 M will decrease the pH value by about 0.05 units.