Difference between revisions of "Benedict's reagent"
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| − | '''Benedict's reagent''', also called '''Benedict's solution''', is a [[reagent]] used to test for [[reducing sugar]]s, named after American chemist [[Stanley Rossiter Benedict]].<ref name="Benedict">{{citation | last = Benedict | first = Stanley R. | authorlink = Stanley Rossiter Benedict | title = A Reagent For the Detection of Reducing Sugars | journal = J. Biol. Chem. | volume = 5 | issue = 6 | pages = 485–87 | year = 1908 | url = http://www.jbc.org/content/5/5/485.full.pdf}}.</ref><ref name="JBC">{{citation | first1 = Robert D. | last1 = Simoni | first2 = Robert L. | last2 = Hill | first3 = Martha | last3 = Vaughan | title = Benedict's Solution, a Reagent for Measuring Reducing Sugars: the Clinical Chemistry of Stanley R. Benedict | journal = J. Biol. Chem. | volume = 277 | issue = 16 | pages = e5 | year = 2002 | url = http://www.jbc.org/content/277/16/e5.full.pdf}}.</ref> Similar to [[Fehling's solution]], it is an alkaline solution of [[Copper|copper(II)]], but it stabilized by [[Citric acid|citrate]] ions rather than [[Tartaric acid|tartrate]] ions and is less corrosive and more stable to storage.<ref name="JBC"/> | + | '''Benedict's reagent''', also called '''Benedict's solution''', is a [[reagent]] used to test for [[reducing sugar]]s, named after American chemist [[Stanley Rossiter Benedict]].<ref name="Benedict">{{citation | last = Benedict | first = Stanley R. | authorlink = Stanley Rossiter Benedict | title = A Reagent For the Detection of Reducing Sugars | journal = J. Biol. Chem. | volume = 5 | issue = 6 | pages = 485–87 | year = 1908 | url = http://www.jbc.org/content/5/5/485.full.pdf}}.</ref><ref name="JBC">{{citation | first1 = Robert D. | last1 = Simoni | first2 = Robert L. | last2 = Hill | first3 = Martha | last3 = Vaughan | title = Benedict's Solution, a Reagent for Measuring Reducing Sugars: the Clinical Chemistry of Stanley R. Benedict | journal = J. Biol. Chem. | volume = 277 | issue = 16 | pages = e5 | year = 2002 | url = http://www.jbc.org/content/277/16/e5.full.pdf}}.</ref> Similar to [[Fehling's solution]], it is an alkaline solution of [[Copper|copper(II)]], but it is stabilized by [[Citric acid|citrate]] ions rather than [[Tartaric acid|tartrate]] ions and is less corrosive and more stable to storage.<ref name="JBC"/> |
==Reagent== | ==Reagent== | ||
| − | The reagent is prepared by dissolving 100 g of anhydrous [[sodium carbonate]], 173 g of [[trisodium citrate]] dihydrate and 17.3 g of [[copper(II) sulfate]] pentahydrate in water, and diluting to 1 litre.<ref name="Benedict"/> The final solution is 71.3 mmol/dm<sup>3</sup> in copper(II) and 588 mmol/dm<sup>3</sup> in total citrate (eightfold excess). The copper(II) is believed to be present as a 1:1 citrate [[complex]], [Cu(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)(OH)(H<sub>2</sub>O)<sub>''n''</sub>]<sup>2-</sup> (''n'' = 0, 1).<ref>{{citation | first1 = Terrence B. | last1 = Field | first2 = Janet L. | last2 = McCourt | first3 = W. A. E. McBryde | title = Composition and Stability of Iron and Copper Citrate Complexes in Aqueous Solution | url = http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3291&volume=52&issue=17&startPage=3119 | journal = Can. J. Chem. | year = 1974 | volume = 52 | pages = 3119–24}}.</ref> | + | The reagent is prepared by dissolving 100 g of anhydrous [[sodium carbonate]], 173 g of [[trisodium citrate]] dihydrate and 17.3 g of [[copper(II) sulfate]] pentahydrate in water, and diluting to 1 litre.<ref name="Benedict"/> The final solution is 71.3 mmol/dm<sup>3</sup> in copper(II) and 588 mmol/dm<sup>3</sup> in total citrate (eightfold excess), with a [[pH]] of about 12. The copper(II) is believed to be present as a 1:1 citrate [[complex]], [Cu(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)(OH)(H<sub>2</sub>O)<sub>''n''</sub>]<sup>2-</sup> (''n'' = 0, 1).<ref>{{citation | first1 = Terrence B. | last1 = Field | first2 = Janet L. | last2 = McCourt | first3 = W. A. E. McBryde | title = Composition and Stability of Iron and Copper Citrate Complexes in Aqueous Solution | url = http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3291&volume=52&issue=17&startPage=3119 | journal = Can. J. Chem. | year = 1974 | volume = 52 | pages = 3119–24}}.</ref> |
==References== | ==References== | ||
Revision as of 11:16, 7 April 2010
Benedict's reagent, also called Benedict's solution, is a reagent used to test for reducing sugars, named after American chemist Stanley Rossiter Benedict.[1][2] Similar to Fehling's solution, it is an alkaline solution of copper(II), but it is stabilized by citrate ions rather than tartrate ions and is less corrosive and more stable to storage.[2]
Reagent
The reagent is prepared by dissolving 100 g of anhydrous sodium carbonate, 173 g of trisodium citrate dihydrate and 17.3 g of copper(II) sulfate pentahydrate in water, and diluting to 1 litre.[1] The final solution is 71.3 mmol/dm3 in copper(II) and 588 mmol/dm3 in total citrate (eightfold excess), with a pH of about 12. The copper(II) is believed to be present as a 1:1 citrate complex, [Cu(C6H5O7)(OH)(H2O)n]2- (n = 0, 1).[3]
References
- ↑ 1.0 1.1 Benedict, Stanley R. A Reagent For the Detection of Reducing Sugars. J. Biol. Chem. 1908, 5 (6), 485–87, <http://www.jbc.org/content/5/5/485.full.pdf>.
- ↑ 2.0 2.1 Simoni, Robert D.; Hill, Robert L.; Vaughan, Martha Benedict's Solution, a Reagent for Measuring Reducing Sugars: the Clinical Chemistry of Stanley R. Benedict. J. Biol. Chem. 2002, 277 (16), e5, <http://www.jbc.org/content/277/16/e5.full.pdf>.
- ↑ Field, Terrence B.; McCourt, Janet L. Composition and Stability of Iron and Copper Citrate Complexes in Aqueous Solution. Can. J. Chem. 1974, 52, 3119–24, <http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3291&volume=52&issue=17&startPage=3119>.
External links
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See also the corresponding article on Wikipedia. |
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