Search results
Results from the WOW.Com Content Network
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.
The following table presents pK a values at 20 °C. Values change by about 0.01 per degree of temperature. [1] [3] Good's original 1966 paper had two older buffers (marked with italics) for comparison. In 1972 Good published a second list with three more buffers, and five more were added in 1980.
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 p K a ± 1. When choosing a buffer for use at a specific pH, it should have a p K a value as close as possible to that pH.
In the case of a phosphate buffer, substantial quantities of weak acid and conjugate weak base (H 2 PO 4 – and HPO 4 2–) can accept or donate protons accordingly in order to conserve intracellular pH: [13] [14] OH – + H 2 PO 4 – ⇌ H 2 O + HPO 4 2– H + + HPO 4 2– ⇌ H 2 PO 4 –
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid, a.k.a. phosphoric acid H 3 PO 4. The phosphate or orthophosphate ion [PO 4] 3− is derived from phosphoric acid by the removal of three protons H +.
McIlvaine buffer is a buffer solution composed of citric acid and disodium hydrogen phosphate, also known as citrate-phosphate buffer. It was introduced in 1921 by the United States agronomist Theodore Clinton McIlvaine (1875–1959) from West Virginia University , and it can be prepared in pH 2.2 to 8 by mixing two stock solutions.
The term phosphate is also used in organic chemistry for the functional groups that result when one or more of the hydrogens are replaced by bonds to other groups. These acids, together with their salts and esters , include some of the best-known compounds of phosphorus, of high importance in biochemistry , mineralogy , agriculture , pharmacy ...
Tripotassium phosphate, also called tribasic potassium phosphate [3] is a water-soluble salt with the chemical formula K 3 PO 4. (H 2 O) x (x = 0, 3, 7, 9). [ 4 ] Tripotassium phosphate is basic: a 1% aqueous solution has a pH of 11.8.