Standard solution— Dissolve an accurately weighed quantity of USP Dextrose RSin water,and dilute quantitatively with water to obtain a solution having a known concentration of about 10mg per mL.

Test solution— Transfer about 5g of Dextrates,accurately weighed,with the aid of hot water to a 500-mLvolumetric flask,cool,add water to volume,and mix.

Procedure— Transfer 25.0-mLportions of alkaline cupric tartrate TSto each of two boiling flasks.Bring the contents of one of the flasks to boiling,and titrate with Standard solutionto within 0.5mLof the anticipated endpoint.Again heat the flask,with swirling,boil moderately for 2minutes,add 2drops of methylene blue solution (1in 100),immediately add about 2drops of the Standard solutionfrom 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 3minutes by adding Standard solutiondropwise,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 0.5mLof 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: in which Ais the percentage Loss on dryingof the Dextrates taken;CUis the concentration,in mg per mL,of Dextrates in the Test solution;CSis the concentration,in mg per mL,of USP Dextrose RSin the Standard solution,and VUand VSare the titrated volumes,in mL,of the Test solutionand the Standard solution,respectively.