Standard preparation— Using Penicillin G Potassium RS,prepare as directed for Standard preparationunderIodometric Assay—Antibiotics á425ñ.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer a portion of the powder,accurately weighed,equivalent to about 200,000Penicillin G Units,to a 100-mLvolumetric flask,add 10mLof 1.0Nsodium hydroxide,and mix.Allow to stand for 15minutes,add 10mLof 1.2Nhydrochloric acid,dilute with water to volume,and mix.Pipet 2mLof this solution into a glass-stoppered,125-mLconical flask.

Blank preparation— Transfer an accurately weighed portion of the powdered Tablets remaining from the preparation of the Assay preparation,equivalent to about 200,000Penicillin G Units,to a 100-mLvolumetric flask,dilute with Buffer No.1to volume,and mix.Pipet 2mLof this solution into a glass-stoppered,125-mLconical flask.

Procedure— Proceed as directed for Procedureunder Iodometric Assay—Antibiotics á425ñ,except in performing the Inactivation and titrationto omit the addition of 1.0Nsodium hydroxide and 1.2Nhydrochloric acid,and in the Blank determinationto use the Blank preparationin place of the Assay preparation.Calculate the quantity,in Penicillin G Units,in the portion of Tablets taken by the formula: in which Tis the labeled quantity,in Penicillin G Units,in each Tablet,and Dis the concentration,in Penicillin G Units per mL,of the Assay preparationon the basis of the labeled quantity in each Tablet and the extent of dilution.