phosphate buffer solution
Noun: A phosphate buffer solution is a specific aqueous solution that contains a phosphate buffer system. Its primary function is to resist changes in pH (a measure of acidity or alkalinity) when small amounts of acid or base are added. It is a standard reagent used to maintain a stable, known pH level in chemical and biological experiments.
This term is used exclusively in scientific contexts, particularly in chemistry, biochemistry, and molecular biology. It refers to a prepared, standardized solution with a defined concentration and pH.
Examples: * The protocol requires washing the cells with phosphate buffer solution before fixation. * To calibrate the pH meter, we used a phosphate buffer solution at pH 7.0. * The enzyme activity was assayed in a phosphate buffer solution.
- Abbreviation: Commonly abbreviated as PBS (Phosphate-Buffered Saline), especially when the solution also contains sodium chloride to make it isotonic for biological tissues. In precise chemical contexts, it may be specified by its exact molarity and pH (e.g., 0.1 M phosphate buffer, pH 7.4).
- Role in Buffering: The solution works because it contains a mixture of a weak acid (e.g., dihydrogen phosphate ion, H₂PO₄⁻) and its conjugate base (e.g., hydrogen phosphate ion, HPO₄²⁻). This pair absorbs excess H⁺ or OH⁻ ions, stabilizing the pH.
- Buffer Solution (n): The general category of solutions that resist pH change. A phosphate buffer solution is one specific type.
- Phosphate-Buffered Saline (PBS) (n): A specific, common variant of a phosphate buffer solution that includes salts to match the osmotic pressure of bodily fluids.
- Tris Buffer (n): Another common biological buffer solution, using a different chemical system (Tris/HCl) to maintain pH.
- Phosphate buffer (often used interchangeably, though "solution" is more precise for the liquid form).
- PBS (in biological contexts).
- To prepare a phosphate buffer solution: The act of making this reagent.
- To resuspend in phosphate buffer solution: A common laboratory instruction for dissolving a pellet in this liquid.
- Phosphate buffer system: Refers to the chemical equilibrium principle (H₂PO₄⁻/HPO₄²⁻) itself, rather than the prepared solution.
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a solution containing a phosphate buffer
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