Tris hydrochloride is used to prepare buffer, mainly at a physiological range of 7.3 to 7.5. This buffer is well-suited with biological fluids. It is used in laboratories as primary pH standard in clinical laboratories. A series of Pre-mixed solutions of TRIZMA Base and TRIZMA HCl to provide commonly used pH values for Tris buffers. No mixing or pH adjustment necessary. Guaranteed accuracy ± 0.1 pH units.