1M HEPES, pH 6.5

HEPES is a zwitterionic buffering agent used extensively in biochemistry and molecular biology. It is effective as a buffer at pH 6.8 to 8.2. The temperature dependence of HEPES is less than TRIS buffer. HEPES (N?2?hydroxyethylpiperazine?N?2?ethane sulfonic acid) is an organic chemical buffering agent. This buffer has low absorbance in the UV range. It interferes with the Lowry protein assay and gives false positive results but not the Biuret protein assay. It is strongly recommended to keep HEPES?containing solutions in darkness as much as possible as it becomes phototoxic when exposed to ambient light by the production of hydrogen peroxide.