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Buffers are aqueous solutions of weak acids and their conjugate bases, or weak bases and their conjugate acids. Buffers show little change in pH when small amounts of strong acids or bases are added. Buffer solutions are used in biological systems to keep pH at a nearly constant value. The pH often plays an important role in a biological process and can affect internal and external environments of tissues and cells. Buffers are often required to maintain the correct pH for proteins and oligonucleotides, as many macromolecules require precise conditions to function properly.
In biological systems an ideal buffer has the following characteristics: a pKa value between 6.0 and 8.0, high water solubility, nontoxic, limited effect on biochemical reactions, very low absorbance between 240nm and 700nm, enzymatic and hydrolytic stability, minimal changes due to temperature and concentration, limited effects due to ionic or salt composition of the solution, and limited interaction with mineral cations. Alfa Aesar offers a complete line of biological buffers including powders and salts and also premixed buffer solutions.