Benedict’s Qualitative Reagent

Benedict s qualitative reagent (for glucose) dissolve 173 g of sodium citrate and 100 g of anhydrous sodium carbonate in about 600 mL of water, and dilute to 850 mL dissolve 17.3 g of CUSO4 5H2O in 100 mL of water and dilute to 150 mL this solution is added to the citrate-carbonate solution with constant stirring. See also the quantitative reagent below. 

Benedict s Qualitative Reagent See Cupric Citrate TS, Alkaline. 

Cupric Citrate TS, Alkaline (Benedict s Qualitative Reagent) With the aid of heat, dissolve 173 g of sodium citrate (C6HjNa307 2HiO) and 117 g of sodium carbonate (Na2-CO3 H2O) in about 700 mL of water, and filter through paper, if necessary. In a separate container, dissolve 17.3 g of cupric sulfate (CuS04-5H20) in about 100 mL of water, and slowly add this solution, with constant stirring, to the first solution. Cool the mixture, dilute to 1000 mL, and mix. 

Bacterial Alpha-Amylase Activity, 789 Bacterial (PC) Proteolytic Activity, 811 Baking Soda, 355 Balances and Weights, 729 Balsam Fir Oil, 156 Balsam Peru Oil, 38, 574 Barium Chloride TS, 850 Barium Diphenylamine Sulfonate TS, 850 Barium Hydroxide TS, (S 1)114 Barium Hydroxide, 0.2 N, 856 Barium Standard Solution, 849 Basil Oil, Comoros Type, 39, 574 Basil Oil, European Type, 39, 579 Basil Oil, Italian Type, 39 Basil Oil, Reunion Type, 39 Basil Oil Exotic, 39 Basil Oleoresin, 391, 392 Bay Leaf Oil, 217 Bay Oil, 40, 575 BCD, (S 1)15 Beeswax, White, 40 Beeswax, Yellow, 41 Beet Fiber, (S1 )45 Beet Sugar, 400, (S2)35 Benedict s Qualitative Reagent, 850, 851 Bentonite, 41 Benzaldehyde, 456, 607 Benzaldehyde Glyceryl Acetal, 456, 607, (S1)60... 

The use of Benedict s qualitative reagent and NaOH solution has been suggested for protein estimation (G6, H9, H28). This practice is not recommended as opalescence may occur during an estimation, although it has been claimed that this opalescence can be removed by ether extraction (H9). Another biuret reagent contains a high concentration of ammonium hydroxide (L9), but is inconvenient to work with and has lower sensitivity to protein. 

Benedict s qualitative reagent must not be confused with his quantitative reagent, which is used only for sugar estimation. 

Benedict s QvMlitative Test.— Add 0-5 ml. of urine (8 drops, not more) to 5 ml. of Benedict s qualitative reagent. Mix, and heat over a small fiame for one to two minutes, or, much better, immerse the tube in boiling water for two to three minutes (this avoids spurting of the mixture). Allow to cool for a few minutes, and observe the appearance. 

Reduction test for pentose and fructose (Lasker and Enklewitz, 1933) Mix 1 ml. of urine and 5 ml. of Benedict s qualitative reagent, and incubate at 65 C., for ten minutes. The appearance of a yellow precipitate indicates that the urine contains L-xyloketose or fructose. Fructosuria, which is very rare, may be detected by the fact that the urine gives a positive fermentation test and yields glucosazone. 

Benedict s Qualitative Copper Reagent 17-3 gm. crystalline CUSO4.5H2O, with 173 gm. Na citrate and 100 gm. anhydrous Na2C03 in 1,000 ml. water. Used for detecting reducing sugars in urine. 

Oxidation with Benedict s reagent (Section 25 19) Sugars that con tain a free hemiacetal function are called reducing sugars They react with copper(ll) sulfate in a sodium citrate/sodium carbonate buffer (Benedict s reagent) to form a red precipitate of copper(l) oxide Used as a qualitative test for reducing sugars... 

Benedict s solution (qualitative reagent for glucose). With... 

Benedict s solution (qualitative reagent for glucose). Dissolve 173 g of sodium citrate and 100 g of sodium carbonate in 800 mL of distilled water. Filter, if necessary, and dilute to 850 mL with distilled water. Dissolve 17.3 g of copper (II) sulfate pen-tahydrate in 100 mL of distilled water. Pour the latter solution, with constant stirring, into the carbonate-citrate solution and dilute to 1 L with distilled water. 

H28. Hussain, Q. Z., Shah, N. S., and Chaudhuri, S. N., Estimation of serum or protein using qualitative Benedict reagent. Clin. Chim. Acta 6, 447-448 (1961). 

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