CAPS 3-[Cyclohexylamino]-1-propanesulfonic acid A common "Good Buffer" because it has a pKa value near physiological pH, it is not absorbed through cell membranes, and it is essentially transparent to UV light. It's used for culturing cells in-vitro and other biological applications. Technical Information:High Purity GradepKa (20°C): 10.40Ref: Good N.E. et al. Biochemistry 5 467 (1966).Appearance: SolidDensity : 1.20 g/cm3 (Predicted)Melting Point: 324 °CPH Value: 9.7 - 11.1RTECS Number: TZ6395000