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Lidstrom:Buffers: Difference between revisions
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* You can make phosphate buffers several ways. The difference between them is how much salt and what type of salt is also present in solution. | * You can make phosphate buffers several ways. The difference between them is how much salt and what type of salt is also present in solution. | ||
** If you want a desired pH, you can use a ratio of hydrogen phosphate and dihydrogen phosphate salts to get the pH you desire. There are tables that correlate desired pH values and concentrations to volumes you should use. | ** If you want a desired pH, you can use a ratio of hydrogen phosphate and dihydrogen phosphate salts to get the pH you desire. There are tables that correlate desired pH values and concentrations to volumes you should use. | ||
*** [[image:2014_02_09 phosphate recipes by mass from sigma.png [http://www.sigmaaldrich.com/life-science/core-bioreagents/biological-buffers/learning-center/buffer-reference-center.html Sigma's recipes] based on mass ]] | *** [[image:2014_02_09 phosphate recipes by mass from sigma.png|thumb|center|upright=2| [http://www.sigmaaldrich.com/life-science/core-bioreagents/biological-buffers/learning-center/buffer-reference-center.html Sigma's recipes] based on mass ]] | ||
** Sodium and potassium phosphates are interchangeable. You can use either based on whether you would rather have Na or K in soltuion. | ** Sodium and potassium phosphates are interchangeable. You can use either based on whether you would rather have Na or K in soltuion. | ||
** You can also start with one buffer and use HCl or NaOH to force the pH in one direction or another. For example, if you add enough HCl to a PO<sub>4</sub><sup>3-</sup> solution, you will force the phosphate into a pH7.4 solution with comparable amounts of HPO<sub>4</sub><sup>2−</sup>) and H2PO<sub>4</sub><sup>−</sup>. | ** You can also start with one buffer and use HCl or NaOH to force the pH in one direction or another. For example, if you add enough HCl to a PO<sub>4</sub><sup>3-</sup> solution, you will force the phosphate into a pH7.4 solution with comparable amounts of HPO<sub>4</sub><sup>2−</sup>) and H2PO<sub>4</sub><sup>−</sup>. | ||
