Petrolatum
»Petrolatum is a purified mixture of semisolid hydrocarbons obtained from petroleum.It may contain a suitable stabilizer.
Packaging and storage—
Preserve in well-closed containers.
Labeling—
Label it to indicate the name and proportion of any added stabilizer.
Color—
Melt about 10g on a steam bath,and pour about 5mLof the liquid into a clear-glass 15-×150-mm test tube,keeping the petrolatum melted.The petrolatum is not darker than a solution made by mixing 3.8mLof ferric chloride CSand 1.2mLof cobaltous chloride CSin a similar tube,the comparison of the two being made in reflected light against a white background,the petrolatum tube being held directly against the background at such an angle that there is no fluorescence.
Specific gravity á841ñ:
between 0.815and 0.880at 60
.
.
Consistency—
Apparatus—
Determine the consistency of Petrolatum by means of a penetrometer fitted with a polished cone-shaped metal plunger weighing 150g,having a detachable steel tip of the following dimensions:the tip of the cone has an angle of 30,the point being truncated to a diameter of 0.381±0.025mm,the base of the tip is 8.38±0.05mm in diameter,and the length of the tip is 14.94±0.05mm.The remaining portion of the cone has an angle of 90,is about 28mm in height,and has a maximum diameter at the base of about 65mm.The containers for the test are flat-bottom metal cylinders that are 100±6mm in diameter and not less than 65mm in height.They are constructed of at least 1.6-mm (16-gauge)metal,and are provided with well-fitting,water-tight covers.
,the point being truncated to a diameter of 0.381±0.025mm,the base of the tip is 8.38±0.05mm in diameter,and the length of the tip is 14.94±0.05mm.The remaining portion of the cone has an angle of 90,is about 28mm in height,and has a maximum diameter at the base of about 65mm.The containers for the test are flat-bottom metal cylinders that are 100±6mm in diameter and not less than 65mm in height.They are constructed of at least 1.6-mm (16-gauge)metal,and are provided with well-fitting,water-tight covers.
Procedure—
Place the required number of containers in an oven,and bring them and a quantity of Petrolatum to a temperature of 82±2.5,pour the Petrolatum into one or more of the containers,filling to within 6mm of the rim.Cool to 25±2.5over a period of not less than 16hours,protected from drafts.Two hours before the test,place the containers in a water bath at 25±0.5.If the room temperature is below 23.5or above 26.5,adjust the temperature of the cone to 25±0.5by placing it in the water bath.
,pour the Petrolatum into one or more of the containers,filling to within 6mm of the rim.Cool to 25±2.5over a period of not less than 16hours,protected from drafts.Two hours before the test,place the containers in a water bath at 25±0.5.If the room temperature is below 23.5or above 26.5,adjust the temperature of the cone to 25±0.5by placing it in the water bath.
Without disturbing the surface of the substance under test,place the container on the penetrometer table,and lower the cone until the tip just touches the top surface of the test substance at a spot 25mm to 38mm from the edge of the container.Adjust the zero setting and quickly release the plunger,then hold it free for 5seconds.Secure the plunger,and read the total penetration from the scale.Make three or more trials,each so spaced that there is no overlapping of the areas of penetration.Where the penetration exceeds 20mm,use a separate container of the test substance for each trial.Read the penetration to the nearest 0.1mm.Calculate the average of the three or more readings,and conduct further trials to a total of 10if the individual results differ from the average by more than ±3%:the final average of the trials is not less than 10.0mm and not more than 30.0mm,indicating a consistency value between 100and 300.
Acidity—
If the addition of phenolphthalein TSin the test for Alkalinityproduces no pink color,add 0.1mLof methyl orange TS:no red or pink color is produced.
Alkalinity—
Introduce 35g into a suitable beaker,add 100mLof boiling water,cover,and place on a stirring hot-plate maintained at the boiling point of water.After 5minutes,allow the phases to separate.Draw off the separated water into a casserole,wash the petrolatum further with two 50-mLportions of boiling water,and add the washings to the casserole.To the pooled washings add 1drop of phenolphthalein TS,and boil:the solution does not acquire a pink color.
Residue on ignition á281ñ—
Heat 2g in an open porcelain or platinum dish over a Bunsen flame:it volatilizes without emitting an acrid odor and on ignition yields not more than 0.1%of residue.
Organic acids—
Weigh 20.0g,add 100mLof a 1in 2mixture of neutralized alcohol and water,agitate thoroughly,and heat to boiling.Add 1mLof phenolphthalein TS,and titrate rapidly with 0.1Nsodium hydroxide VS,with vigorous agitation to the production of a sharp pink endpoint,noting the color change in the alcohol-water layer:not more than 400µLof 0.100Nsodium hydroxide is required.
Fixed oils,fats,and rosin—
Digest 10g with 50mLof 5Nsodium hydroxide at 100for 30minutes.Separate the water layer,and acidify it with 5Nsulfuric acid:no oily or solid matter separates.
for 30minutes.Separate the water layer,and acidify it with 5Nsulfuric acid:no oily or solid matter separates.
Auxiliary Information—
Staff Liaison:Justin Lane,B.S.,Scientific Associate
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 1523
Pharmacopeial Forum:Volume No.28(2)Page 569
Phone Number:1-301-816-8323