(dex' trates).
» Dextrates is a purified mixture of saccharides resulting from the controlled enzymatic hydrolysis of starch. It is either anhydrous or hydrated. Its dextrose equivalent is not less than 93.0 percent and not more than 99.0 percent, calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers, in a cool, dry place.
Labeling— Label it to state whether it is anhydrous or hydrated.
USP Reference standards 11
USP Dextrose RS Click to View Structure
pH 791: between 3.8 and 5.8, determined in a 1 in 5 solution in carbon dioxide-free water.
Loss on drying 731 Dry it at 105 for 16 hours in a convection oven: the anhydrous form loses not more than 2.0% of its weight; the hydrated form loses between 7.8% and 9.2% of its weight.
Residue on ignition 281: not more than 0.1%.
Dextrose equivalent—
Standard solution— Dissolve an accurately weighed quantity of USP Dextrose RS in water, and dilute quantitatively with water to obtain a solution having a known concentration of about 10 mg per mL.
Test solution— Transfer about 5 g of Dextrates, accurately weighed, with the aid of hot water to a 500-mL volumetric flask, cool, add water to volume, and mix.
Procedure— Transfer 25.0-mL portions of alkaline cupric tartrate TS to each of two boiling flasks. Bring the contents of one of the flasks to boiling, and titrate with Standard solution to within 0.5 mL of the anticipated endpoint. Again heat the flask, with swirling, boil moderately for 2 minutes, add 2 drops of methylene blue solution (1 in 100), immediately add about 2 drops of the Standard solution from the buret, and again bring to a boil. Allow the cuprous oxide to settle slightly, and observe the color of the supernatant. Complete the titration within 3 minutes by adding Standard solution dropwise, and boiling after each addition, to the disappearance of the blue color, determined by viewing against a white background in daylight or under equivalent illumination. If more than 0.5 mL of the titrant was required after the addition of the indicator, repeat the titration, adding the necessary volume of titrant before adding the indicator. Bring the contents of the second flask to boiling, and similarly titrate with Test solution. Calculate the Dextrose equivalent, on the dried basis, taken by the formula:
[100 / (1 0.01A)](CS / CU)(VS / VU)
in which A is the percentage Loss on drying of the Dextrates taken; CU is the concentration, in mg per mL, of Dextrates in the Test solution; CS is the concentration, in mg per mL, of USP Dextrose RS in the Standard solution, and VU and VS are the titrated volumes, in mL, of the Test solution and the Standard solution, respectively.
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Monograph Robert H. Lafaver, M.S.
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(EXC2010) Monographs - Excipients
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USP35–NF30 Page 1780