Benedict's reagent (also called Benedict's solution or Benedict's test) is a chemical reagent named after an American chemist, Stanley Rossiter Benedict. A reagent or reactant is a substance or compound consumed during a Chemical reaction. Stanley Rossiter Benedict ( 17 March 1884 – 21 December 1936) is an American chemist best known for discovering Benedict's ^[1]

Benedict's reagent is used as a test for the presence of all monosaccharides, and generally also reducing sugars. Monosaccharides (from Greek monos: single sacchar: sugar are the most basic unit of Carbohydrates They consist of one sugar and A reducing sugar is any sugar that in basic solution forms some Aldehyde or Ketone. These include glucose, galactose, mannose, lactose and maltose. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Galactose (Gal (also called brain sugar) is a type of Sugar which is less sweet than Glucose. Mannose is a Sugar Monomer of the Hexose series of Carbohydrates Metabolism Mannose enters the carbohydrate Metabolism Lactose (also referred to as milk sugar) is a Sugar which is found most notably in Milk. Maltose, or malt sugar is a Disaccharide formed from two units of Glucose joined with an α(1→4 linkage Even more generally, Benedict's test will detect the presence of aldehydes (except aromatic ones), and alpha-hydroxy-ketones, including those that occur in certain ketoses. An aldehyde is an organic compound containing a terminal Carbonyl group. Thus, although the ketose fructose is not strictly a reducing sugar, it is an alpha-hydroxy-ketone, and gives a positive test because it is converted to the aldoses glucose and mannose by the base in the reagent. Fructose (also levulose or laevulose) is a simple reducing Sugar ( Monosaccharide) found in many foods and is one of the three Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Mannose is a Sugar Monomer of the Hexose series of Carbohydrates Metabolism Mannose enters the carbohydrate Metabolism ^[2].

Benedict's reagent can be prepared from sodium carbonate, sodium citrate and copper(II) sulfate. Sodium carbonate (also known as washing soda or soda ash), is a Sodium Salt of Carbonic acid. Sodium citrate usually refers to Trisodium citrate, though it can refer to any of the sodium Salts of Citric acid: Monosodium citrate Copper(II sulfate is the Chemical compound with the formula Cu[[Sulfur S]] O 4 ^[3] It is often used in place of Fehling's solution. Fehling's solution is a Solution used to differentiate between water soluble Aldehyde and Ketone Functional groups although Ketose

Benedict's reagent contains blue copper(II) ions (Cu²⁺) which are reduced to copper(I) (Cu⁺). These are precipitated as red copper(I) oxide which is insoluble in water. Precipitation is the formation of a Solid in a Solution during a Chemical reaction. Copper(I oxide or cuprous oxide (Cu2O is an Oxide of Copper. It is Insoluble in water and organic Solvents.

Chemical test

To test for the presence of monosaccharides and reducing disaccharide sugars in food, the food sample is dissolved in water, and a small amount of Benedict's reagent is added. The mixture is heated in a boiling water bath, and any precipitate formed is recorded as a positive result for the presence of reducing sugars in the food.

The common disacharrides lactose and maltose are directly detected by Benedict's reagent, because each contains a glucose with a free reducing aldehyde moiety, after isomerization.

Sucrose (table sugar) contains two sugars (fructose and glucose) joined with by their glycosidic bond in such a way as to prevent the glucose isomerizing to aldehyde, or the fructose to alpha-hydroxy-ketone form. Solubility of Pure SucroseTemperature(Cg Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. In Chemistry, a glycosidic bond is a certain type of Functional group that joins a Carbohydrate (sugar molecule to another which may be another carbohydrate Sucrose is thus a non-reducing sugar which does not react with Benedict's reagent. Sucrose indirectly produces a positive result with Benedict's reagent if heated with dilute hydrochloric acid prior to the test, although after this treatment it is no longer sucrose. The acidic conditions and heat break the glycosidic bond in sucrose through hydrolysis. In Chemistry, a glycosidic bond is a certain type of Functional group that joins a Carbohydrate (sugar molecule to another which may be another carbohydrate Hydrolysis is a Chemical reaction during which one or more water molecules are split into hydrogen and hydroxide ions which may go on to participate in further reactions The products of sucrose decomposition are glucose and fructose, both of which can be detected by Benedict's reagent, as described above.

Starches do not react or react very poorly with Benedict's reagent, due to the relatively small number of reducing sugar moieties, which occur only at the ends of carbohydrate chains. Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide Inositol (myo-inositol) is another carbohydrate which produces a negative test. Inositol, (of which the most prominent naturally occurring form is myo -inositol cis -1235- trans -46-cyclohexanehexol) is a carbocyclic

Benedict's reagent can be used to test for the presence of glucose in urine. Urine is a liquid waste product of the body secreted by the Kidneys by a process of filtration from Blood and Excreted through the Urethra. Glucose found to be present in urine is an indication of diabetes mellitus. Diabetes mellitus (ˌdaɪəˈbiːtiːz or /ˌdaɪəˈbiːtəs/ /məˈlaɪtəs/ or /ˈmɛlətəs/ often referred to simply as diabetes ( Ancient Greek: grc Once a reducing sugar is detected in urine, further tests have to be undergone in order to ascertain which sugar is present. Only glucose is indicative of diabetes.

Quantitative reagent

Benedict's quantitative reagent is used to determine how much reducing sugar is present. A quantitative attribute is one that exists in a range of magnitudes and can therefore be measured. This solution forms as white precipitate rather than a red one and so can be used in a titration. Titration is a common laboratory method of Quantitative chemical analysis that is used to determine the unknown Concentration of a known Reactant The titration should be repeated with 1% glucose solution instead of the sample for calibration. Calibration is the process of establishing the relationship between a measuring device and the units of measure

References

1. ^ Benedict, S. R. (1908). "A Reagent For the Detection of Reducing Sugars". J. Biol. Chem. 5: 485–487.  
2. ^ Fehling's Test for Reducing Sugars
3. ^ Robert D. Simoni, Robert L. Hill, and Martha Vaughan (2002). "Benedict's Solution, a Reagent for Measuring Reducing Sugars: the Clinical Chemistry of Stanley R. Benedict". J. Biol. Chem. 277 (16): 10-11.  

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