C6H10O6 178.14

D-Gluconic acid d-lactone.
Glucono delta-lactone [90-80-2].

Packaging and storage— Preserve in well-closed containers.

Identification— Dissolve about 0.5g in 5mLof warm water in a test tube.Add 1mLof freshly distilled phenylhydrazine,and heat on a steam bath for 30minutes.Cool the solution,induce crystallization by scratching the inner surface of the test tube with a glass rod,and collect the crystals of the phenylhydrazide of gluconic acid.Dissolve the crystals in 10mLof hot water to which a small amount of activated charcoal has been added,filter,recrystallize,wash the crystals with 2mLof cold water,and dry the crystals at 105for 1hour:the crystals so obtained melt between 195and 200.

Lead á251ñ— Prepare a Test Preparation as directed in the chapter,and use 10mLof Diluted Standard Lead Solution (10µg of lead)for the test:the limit is 0.001%.

Heavy metals á231ñ— Dissolve 1g in 25mLof water:the limit is 0.002%.

Reducing substances— Transfer 10.0g to a 400-mLbeaker,add 40mLof water,and swirl to dissolve.Add 2drops of phenolphthalein TS,and neutralize with sodium hydroxide solution (1in 2).Dilute with water to about 50mL,and add 50mLof alkaline cupric tartrate TS.Heat so that the solution begins to boil in 4minutes,and allow boiling to continue for 120seconds.Pass the suspension through a medium-porosity filtering crucible,and wash the filter with three 5-mLportions of water.Place the crucible in an upright position in the original beaker,add 5mLof water and 3mLof nitric acid to the crucible,mix with a glass rod to ensure complete solution of the cuprous oxide,and wash the solution from the crucible into a beaker with the aid of 5mLof water.Add bromine TS,usually 5to 10mL,until the solution becomes yellow in color,and dilute with water to about 75mL.Add a few glass beads,boil until the bromine has been driven off,and cool.Slowly add ammonium hydroxide until a deep blue color appears,then adjust with glacial acetic acid to a pHof 4,and add water to make about 100mL.Add 4g of potassium iodide,and titrate with 0.1Nsodium thiosulfate VS,adding starch TSjust before the endpoint is reached:not more than 16.1mLof 0.1Nsodium thiosulfate is consumed.

Assay— Dissolve about 600mg of Gluconolactone,accurately weighed,in 100mLof water in a 300-mLconical flask,add 50.0mLof 0.1Nsodium hydroxide VS,and allow to stand for 15minutes.Add phenolphthalein TS,and titrate the excess alkali with 0.1Nhydrochloric acid VS.Perform a blank determination (see Residual Titrationsunder Titrimetry á541ñ).Each mLof 0.1Nsodium hydroxide is equivalent to 17.81mg of C6H10O6.

Expert Committee:(PA4)Pharmaceutical Analysis 4

USP28–NF23Page 908

Phone Number:1-301-816-8251