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pK a: Because most biological reactions take place near-neutral pH between 6 and 8, ideal buffers would have pK a values in this region to provide maximum buffering capacity there. Solubility: For ease in handling and because biological systems are in aqueous systems, good solubility in water was required.
Buffer capacity falls to 33% of the maximum value at pH = pK a ± 1, to 10% at pH = pK a ± 1.5 and to 1% at pH = pK a ± 2. For this reason the most useful range is approximately pK a ± 1. When choosing a buffer for use at a specific pH, it should have a pK a value as close as possible to that pH. [2]
The useful buffer range for tris (pH 7–9) coincides with the physiological pH typical of most living organisms. This, and its low cost, make tris one of the most common buffers in the biology/biochemistry laboratory. Tris is also used as a primary standard to standardize acid solutions for chemical analysis.
Tris-buffered saline (TBS) is a buffer used in some biochemical techniques to maintain the pH within a relatively narrow range. Tris (with HCl) has a slightly alkaline buffering capacity in the 7–9.2 range. The conjugate acid of Tris has a pK a of 8.07 at 25 °C.
Phosphate-buffered saline (PBS) is a buffer solution (pH ~ 7.4) commonly used in biological research. It is a water-based salt solution containing disodium hydrogen phosphate, sodium chloride and, in some formulations, potassium chloride and potassium dihydrogen phosphate. The buffer helps to maintain a constant pH.
MOPS (3-(N-morpholino)propanesulfonic acid) is a buffer introduced in the 1960s, one of the twenty Good's buffers. It is a structural analog to MES, [1] and like MES, its structure contains a morpholine ring. HEPES is a similar pH buffering compound that contains a piperazine ring.
Human brains today contain 50% more plastic than in 2016, a new study found. Brain of people diagnosed with dementia had the most. Human brain samples contain an entire spoon’s worth of ...
HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic sulfonic acid buffering agent.It is one of the twenty Good's buffers.HEPES is widely used in cell culture, largely because it is better at maintaining physiological pH despite changes in carbon dioxide concentration (produced by aerobic respiration) when compared to bicarbonate buffers, which are also commonly used in ...