Zwitterionic buffering substance for a pH range of 5.8 – 7.2 (1).Bis-Tris is used in biochemistry and molecular biology and is a common component of many buffer systems for electrophoresis. Since it may form a complex with some common metals, such as Cu(II) and Pb(II), formation constants should be taken into account when using this buffer in a solution containing metal ions. Bis-Tris is a substitute for the highly toxic buffer cacodylate. Zwitterionic buffering substance for a pH range of 5.8 – 7.2 (1).Bis-Tris is used in biochemistry and molecular biology and is a common component of many buffer systems for electrophoresis. Since it may form a complex with some common metals, such as Cu(II) and Pb(II), formation constants should be taken into account when using this buffer in a solution containing metal ions. Bis-Tris is a substitute for the highly toxic buffer cacodylate.