Benedict's reagent

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Benedict's solution, deep-blue alkaline solution used to test for the presence of the aldehyde functional group, -CHO. The substance to be tested is heated with Benedict's solution; formation of a brick-red precipitate indicates presence of the aldehyde group. Since simple sugars (e.g., glucose) give a positive test, the solution is used mostly in the Biology Department in the food test practicals. It reacts chemically like Fehling's solution; the Cu2+ ion (complexes with citrate ions) is then reduced to Cu+ ion by the aldehyde group (which is oxidized), and precipitates as Copper (1) oxide, Cu2O.

Make sure that you purchase and are using the correct Benedict's reagent. Benedict's is sold as "quantitative" Benedict's and "qualitative" Benedict's.


Benedict's quantitative reagent is used to determine how much reducing sugar is present. This solution forms as white precipitate rather than a red one and so can be used in a titration. The titration should be repeated with 1% glucose solution instead of the sample for calibration. [From Wikipedia]

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