Nitrofurazone Ointment
»Nitrofurazone Ointment is Nitrofurazone in a suitable water-miscible base.It contains not less than 90.0percent and not more than 110.0percent of the labeled amount of nitrofurazone (C6H6N4O4).
NOTE—Avoid exposure at all times to direct sunlight,excessive heat,strong fluorescent lighting,and alkaline materials.
Packaging and storage— Preserve in tight,light-resistant containers.Avoid exposure to direct sunlight,strong fluorescent lighting,and excessive heat.
Completeness of solution— One g dissolves in 9mLof water to form a clear solution.
Identification— Dissolve 400mg of potassium hydroxide in a mixture of 9.5mLof alcohol and 0.5mLof methanol.Immediately before use,dilute with dimethylformamide to 100mL.To 10mLof this solution add a quantity of Ointment,equivalent to about 10µg of nitrofurazone,and mix:a purple solution results.
Assay— [NOTE—Protect from light all solutions that contain nitrofurazone.]
Triethylamine buffer— Transfer 100mLof triethylamine to a 1000-mLvolumetric flask.Add about 800mLof water,and cautiously add 80mLof phosphoric acid.Mix,allow to cool to ambient temperature,dilute with water to volume,mix,and pass through a nylon filter having a 0.5-µm or finer porosity.
Mobile phase— Prepare a filtered and degassed mixture of water,acetonitrile,and Triethylamine buffer(790:200:10).Make any necessary adjustments (see System Suitabilityunder Chromatography á621ñ).
Standard preparation— Transfer about 50mg of USP Nitrofurazone RS,accurately weighed,to a 50-mLlow-actinic volumetric flask,add 10mLof dimethylformamide,and swirl to dissolve.Dilute with alcohol to volume,and mix.Transfer 10.0mLof this solution to a 100-mLlow-actinic volumetric flask,dilute with alcohol to volume,and mix.Transfer 10.0mLof this solution to a 100-mLlow-actinic volumetric flask containing 15mLof alcohol,dilute with water to volume,and mix.This solution contains about 0.01mg of USP Nitrofurazone RSper mL.
Assay preparation— Transfer an accurately weighed portion of Ointment,equivalent to about 1mg of nitrofurazone,to a 100-mLlow-actinic volumetric flask.Add 0.2mLof dimethylformamide and about 25mLof alcohol,and sonicate for about 35minutes.Dilute with water to volume,mix,and pass through a nylon filter having a 0.5-µm or finer porosity.Use the filtrate.
Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 365-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency determined from the nitrofurazone peak is not less than 1500theoretical plates,and the relative standard deviation for replicate injections is not more than 2%.
Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the reponses for the major peaks.Calculate the quantity,in mg,of nitrofurazone (C6H6N4O4)in the portion of Ointment taken by the formula:
100C(rU/rS),
in which Cis the concentration,in mg per mL,of USP Nitrofurazone RSin the Standard preparation;and rUand rSare the nitrofurazone peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 1384
Phone Number:1-301-816-8394
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