Change to read:

(Postponed indefinitely)USP28

Add the following:

Change to read:

100S/(S+r),

Standard solution— Transfer to a 100-mLvolumetric flask about 200mg of acetone,300mg of dehydrated alcohol,and 1000mg of dioxane,each accurately weighed,and mix.Dilute with water to volume,and mix.Transfer 5.0mLof the resulting solution to a 50-mLvolumetric flask,dilute with water to volume,and mix.This solution contains about 0.2mg of acetone,0.3mg of C2H5OH,and 1mg of dioxane per mL.

Solvent— Transfer about 100mg of dioxane,accurately weighed,to a 100-mLvolumetric flask,dilute with water to volume,and mix.

Test solution— Dissolve about 200mg of Doxorubicin Hydrochloride in 3.0mL(3.0g)of Solvent.

Chromatographic system(see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector and a 4-mm ×2-m column packed with 8%to 10%liquid phase G16and 2%potassium hydroxide on 100-to 120-mesh support S1A.The column is maintained at about 60,and helium is used as the carrier gas.Adjust the column temperature and carrier gas flow rate so that dioxane elutes in about 6minutes.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.2for acetone,0.5for alcohol,and 1.0for dioxane;the resolution,R,between adjacent peaks is not less than 2.0;the tailing factor for the alcohol peak is not more than 1.5;and the relative standard deviations of the ratios of the peak responses of the acetone and dioxane peaks and of the alcohol and dioxane peaks for replicate injections is not more than 4.0%.

Procedure— Separately inject equal volumes (about 1µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the percentage,by weight,of acetone (CH3COCH3)and alcohol (C2H5OH),respectively,in the portion of Doxorubicin Hydrochloride taken by the same formula: in which CAis the concentration,in mg per mL,of acetone or alcohol in the Standard solution;CDis the concentration,in mg per mL,of dioxane in the Standard solution;DUis the total quantity,in mg,of dioxane in the Test preparation;WUis the quantity,in mg,of Doxorubicin Hydrochloride taken to prepare the Test solution;and RUand RSare the area ratios of the analyte peak (acetone or alcohol)to the dioxane peak obtained from the Test solutionand the Standard solution,respectively:not more than 0.5%of acetone is found;and the total of acetone and alcohol is not greater than 2.5%.Use the combined percentage of acetone and alcohol obtained to calculate the result obtained as directed in the Assayon the solvent-free basis.

Mobile phase— Prepare a suitable mixture of water,acetonitrile,methanol,and phosphoric acid (540:290:170:2).Dissolve 1g of sodium lauryl sulfate in 1000mLof this solution,adjust with 2Nsodium hydroxide to a pHof 3.6±0.1,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Resolution solution— Dissolve about 10mg of Doxorubicin Hydrochloride in 5mLof water,add 5mLof phosphoric acid,and allow to stand for about 30minutes.Adjust with 2Nsodium hydroxide (about 37mL)to a pHof 2.6±0.1,add 15mLof acetonitrile and 10mLof methanol,mix,and filter.[NOTE—Portions of this solution may be frozen until needed,then thawed,and mixed before use.]

Standard preparation— Dissolve an accurately weighed quantity of USP Doxorubicin Hydrochloride RSin Mobile phaseto obtain a solution having a known concentration of about 0.1mg per mL.

Assay preparation— Transfer about 20mg of Doxorubicin Hydrochloride,accurately weighed,to a 200-mLvolumetric flask,add Mobile phaseto volume,and mix.

Chromatographic system(see Chromatography á621ñ)— The chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L13.The flow rate is about 1.5mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the tailing factor for the doxorubicin peak is not less than 0.7and not more than 1.2;the column efficiency,determined from the doxorubicin peak,is not less than 2250theoretical plates;and the relative standard deviation for replicate injections is not more than 1.0%.Chromatograph the Resolution solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.6for doxorubicinone and 1.0for doxorubicin;and the resolution,R,between the doxorubicinone peak and the doxorubicin peak is not less than 5.5.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C27H29NO11·HCl in the Doxorubicin Hydrochloride taken by the formula: in which Cis the concentration,in mg,of USP Doxorubicin Hydrochloride RSin each mLof the Standard preparation;Pis the content,in µg per mg,of C27H29NO11·HCl in the USP Doxorubicin Hydrochloride RS;and rUand rSare the responses of the doxorubicin peak obtained from the Assay preparationand the Standard preparation,respectively.