Skip to main content
Select Source:

Buffer

Buffer

A buffer is a solution that resists changes in pH upon the addition of acid or base. Buffers typically contain several species that react with added acid and base.

Buffers are important in maintaining the proper environment within microorganisms and within other cells, including those in man. In the microbiology laboratory, many solutions and growth media are buffered to prevent sudden and adverse changes in the acidity or alkalinity of the environment surrounding the microorganisms.

Blood is an example of a natural buffer. In water, small volumes of an acid or base solution can greatly change the pH (measure of the hydrogen ion concentration). If the same amount of the acid or base solution is added to blood, the normal pH of the blood (7.4) changes only marginally. Blood and many other bodily fluids are naturally buffered to resist changes in pH.

In order to explain the properties of a buffer, it is useful to consider a specific example, the acetic acid/acetate buffer system. When acid (e.g., HCl, hydrochloric acid) is added to this buffer, the added hydronium ion (H +) reacts with the strongest base in the medium, namely the acetate ion, to form more acetic acid. This reaction uses up the added hydronium ion, preventing the pH from rising drastically, and is responsible for the buffering effect. As a result of adding acid to the buffer, the concentration of acetate decreases and the concentration of acetic acid increases. The solution acts as a buffer because nearly all of the added hydronium ion is consumed by reaction with acetate. As the hydrogen ion concentration increases, the acetate concentration and acetic acid concentration must adjust. The pH changes slightly to reflect the shift in the concentrations, but the change is much smaller than in the absence of the buffer because most of the added acid is consumed by its reaction with the acetate ion. This example of an acetic acid/acetate ion buffer is typical of other buffer systems.

Buffers are vitally important in living prokaryotic and eukaryotic systems. The rates of various biochemical reactions are very sensitive to the availability of hydronium ions. Many biochemical reactions (e.g., metabolism , respiration , the transmission of nerve impulses, and muscle contraction and relaxation) take place only within a narrow range of pH.

An important buffer in the blood is the bicarbonate ion and dissolved carbon dioxide in the form of carbonic acid. The acidity or alkalinity of the blood can be altered by the ingestion of acidic or basic substances. The carbonate/bicarbonate buffer system compensates for such additions and maintains the pH within the required range.

This buffering system is intimately tied to respiration, and an exceptional feature of pH control by this system is the role of ordinary breathing in maintaining the pH. Carbon dioxide is a normal product of metabolism. It is transported to the lungs, where it is eliminated from the body with every exhalation. However, carbon dioxide in blood is converted to carbonic acid, which dissociates to produce the hydrogen carbonate ion and the hydronium ion. If a chemical reaction or the ingestion of an acidic material increases the hydronium ion concentration in the blood, bicarbonate ion reacts with the added hydronium ion and is transformed into carbonic acid. As a result the concentration of dissolved carbon dioxide in the blood increases. Respiration increases, and more carbon dioxide is expelled from the lungs. Conversely, if a base is ingested, the hydronium ion reacts with it, causing a decrease in the concentration of hydronium ion. More carbonic acid dissociates to restore the hydronium ion consumed by the base. This requires more carbon dioxide to be dissolved in the blood, so respiration is decreased and more gas is retained.

To act as a buffer, a solution must maintain a nearly constant pH when either acid or base is added. Two considerations must be made when a buffer is prepared: (1) Which pH is desired to maintain? The desired pH defines the range of the buffer. (2) How much acid or base does the solution need to consume without a significant change in pH? This defines the capacity of the buffer. The desired pH also determines the compounds used in making up the buffer. The quantity of acid or base the buffer must be able to consume determines the concentrations of the components that must be used, and which allows biological reactions to take place consistently.

See also Biochemical analysis techniques; Laboratory techniques in microbiology

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Buffer." World of Microbiology and Immunology. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"Buffer." World of Microbiology and Immunology. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/buffer

"Buffer." World of Microbiology and Immunology. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/buffer

buffer

buffer
1. A temporary memory for data, normally used to accommodate the difference in the rate at which two devices can handle data during a transfer. The buffer may be built into a peripheral device, such as a printer or disk drive, or may be part of the system's main memory. See buffering.

2. A means of maintaining a short but varying length of magnetic tape between the reels and the capstan and head area of a tape transport, in order that the acceleration of the tape at the reels need not be as great as that of the tape at the capstan. There are two principal types of buffer: tension arm and vacuum column. In the first, the tape passes over a series of rollers, alternate rollers being fixed in position and the rest being attached to a sprung pivoted arm, so that a variable length of tape is taken up in the resulting loops; in the second, the tape is drawn by a difference of pressure into a chamber whose width is just that of the tape. Vacuum column transports are more expensive and noisier but can handle higher tape speeds.

Streaming tape transports and many types of cartridge drives do not use buffers and are therefore limited to lower accelerations of the tape in the area of the head and (if there is one) capstan.

3. Any circuit or device that is put between two others to smooth changes in rate or level or allow asynchronous operation. For example, line drivers can be used to isolate (or buffer) two sets of data lines.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." A Dictionary of Computing. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." A Dictionary of Computing. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/computing/dictionaries-thesauruses-pictures-and-press-releases/buffer-0

"buffer." A Dictionary of Computing. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/computing/dictionaries-thesauruses-pictures-and-press-releases/buffer-0

buffer

buffer A solution that resists change in pH when an acid or alkali is added or when the solution is diluted. Acidic buffers consist of a weak acid with a salt of the acid. The salt provides the negative ion A, which is the conjugate base of the acid HA. An example is carbonic acid and sodium hydrogencarbonate, in which molecules H2CO3 and ions HCO3 are present. When acid is added most of the extra protons are removed by the base: HCO3 + H+ → H2CO3

When base is added, most of the extra hydroxide ions are removed by reaction with undissociated acid: OH + H2CO3 → HCO3 + H2O

Thus, the addition of acid or base changes the pH very little. Basic buffers have a weak base and a salt of the base (to provide the conjugate acid).Natural buffers occur in living organisms, where the biochemical reactions are very sensitive to change in pH (see acid–base balance). The main natural buffers are H2CO3/HCO3 and H2PO4/HPO42– (see also haemoglobinic acid). Buffer solutions are also used in the laboratory (e.g. to keep microscopical preparations at their original pHs in order to prevent the formation of artefacts), in medicine (e.g. in intravenous injections), in agriculture, and in many industrial processes (e.g. fermentation processes).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." A Dictionary of Biology. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." A Dictionary of Biology. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/buffer-1

"buffer." A Dictionary of Biology. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/buffer-1

buffer

buff·er / ˈbəfər/ • n. 1. a person or thing that prevents incompatible or antagonistic people or things from coming into contact with or harming each other: family and friends can provide a buffer against stress. 2. (also buffer solution) Chem. a solution that resists changes in pH when acid or alkali is added to it. Buffers typically involve a weak acid or alkali together with one of its salts. 3. Comput. a temporary memory area or queue used when transferring data between devices or programs operating at different speeds. • v. [tr.] 1. lessen or moderate the impact of (something): the massage helped to buffer the strain. 2. treat with a chemical buffer.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/buffer-0

"buffer." The Oxford Pocket Dictionary of Current English. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/buffer-0

buffer

buffer, solution that can keep its relative acidity or alkalinity constant, i.e., keep its pH constant, despite the addition of strong acids or strong bases. Buffer solutions are frequently solutions that contain either a weak acid and one of its salts or a weak base and one of its salts. Many acid-base reactions take place in living organisms. However, for organisms to perform certain vital functions, the body fluids associated with these functions must maintain a constant pH. For example, blood must maintain a pH of close to 7.4 in order to carry oxygen from the lungs to cells; blood is therefore a powerful buffer.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/buffer

"buffer." The Columbia Encyclopedia, 6th ed.. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/buffer

buffer

buffer A solution of a weak acid and its conjugate weak base that resists changes in pH which would otherwise result from the addition of an acid or base. The buffering properties of weak electrolytes in living organisms are of great importance, since most cells can survive only within narrow pH limits.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." A Dictionary of Ecology. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." A Dictionary of Ecology. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/buffer

"buffer." A Dictionary of Ecology. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/buffer

buffer

buffer A solution of a weak acid and its conjugate weak base that resists changes in pH that would otherwise result from the addition of an acid or base. The buffering properties of weak electrolytes in living organisms are of great importance, since most cells can survive only within narrow pH limits.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." A Dictionary of Plant Sciences. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." A Dictionary of Plant Sciences. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/buffer-0

"buffer." A Dictionary of Plant Sciences. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/buffer-0

buffer

buffer1 fellow. XVIII. prob. ult. from an imit. base *buff -blow, puff, make the sound of a soft blow, whence the meanings ‘stammerer’ XIV, ‘soft fellow’ (dial.); see next.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/buffer-1

"buffer." The Concise Oxford Dictionary of English Etymology. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/buffer-1

buffer

buffer (buf-er) n. a solution whose hydrogen ion concentration (pH) remains virtually unchanged by dilution or by the addition of acid or alkali. See also acid-base balance.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." A Dictionary of Nursing. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." A Dictionary of Nursing. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/buffer

"buffer." A Dictionary of Nursing. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/buffer

buffer

buffer2 device for deadening the force of concussion. XIX. prob. f. buff vb., sound as a soft body when struck.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/buffer-2

"buffer." The Concise Oxford Dictionary of English Etymology. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/buffer-2

buffer

bufferchaffer, gaffer, Jaffa, kafir, Staffaalfalfa, alpha, Balfour, Wadi Halfa •camphor, chamfer •Luftwaffe •laugher, staffer •heifer, zephyr •chafer, trefa, wafer •cockchafer •feoffor, reefer •differ, sniffer •pilfer • titfer • umbellifer • Jennifer •conifer • apocrypha • thurifer •crucifer, Lucifer •Potiphar • aquifer •cipher, encipher, fifer, Haifa, knifer, lifer •coffer, cougher, Offa, offer, proffer, quaffer, scoffer •golfer • phosphor • Forfar • Altdorfer •chauffeur, gofer, goffer, gopher, loafer, Nuku'alofa, Ophir, shofar, sofa •Fraunhofer •hoofer, loofah, opera buffa, roofer, spoofer, tufa, woofer •waterproofer •bluffer, buffer, duffer, puffer, snuffer, suffer •sulphur (US sulfur) • telegrapher •calligrapher, serigrapher •autobiographer, bibliographer, biographer, cartographer, choreographer, cinematographer, crystallographer, geographer, Hagiographa, hagiographer, iconographer, lexicographer, lithographer, oceanographer, palaeographer (US paleographer), photographer, pornographer, radiographer, stenographer, topographer, typographer •philosopher, theosopher •metaphor • Christopher • surfer •Bonhoeffer • windsurfer

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"buffer." Oxford Dictionary of Rhymes. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

"buffer." Oxford Dictionary of Rhymes. . Encyclopedia.com. (August 17, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/buffer

"buffer." Oxford Dictionary of Rhymes. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/buffer