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]]. Similar to [[Fehling's solution]], it is an alkaline solution of [[Copper|copper(II)]] stabilized by [[Citric acid|citrate]] ions. | + | '''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"/> |
==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. 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). 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 12:15, 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 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). 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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