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 6 mg per mL.
Procedure
Transfer 25.0-mL portions of
alkaline cupric tartrate TS to each of two boiling flasks. Bring the contents of one flask to boiling within about 2 minutes while titrating with
Standard solution to within 0.5 mL of the anticipated endpoint. Boil gently for 2 minutes. Continue to boil gently, add 2 drops of methylene blue solution (1 in 100), and complete the titration within 1 minute by adding the
Standard solution dropwise or in small increments until the blue color disappears, 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 the
Test solution. Calculate the dextrose equivalent, on the anhydrous basis, taken by the formula:
[100 / (1 0.01A)] (500)(CS / W)(VS / VU)
in which
A is the percentage
Water of the Liquid Glucose taken; 500 is the volume, in mL, of the
Test solution; W is the weight, in mg, of Liquid Glucose taken to prepare 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. The dextrose equivalent is not less than 90% and not more than 110% of the labeled value.
NF27