Stearic Acid M - uspnf.com

1 Stage 6 HarmonizationOfficial May 1, molecular weight of potassium hydroxide, AcidAcceptance criteria: 194 212 Portions of this monograph that are national USP text, and C. The retention times of the major peaks of the Sampleare not part of the harmonized text, are marked withsolution correspond to those of the Standard solution, assymbols ( ) to specify this in the acid;ASSAYS tearic acid [57-11-4]. PROCEDUREB oron trifluoride methanol solution: 140g/L of bo-DEFINITIONron trifluoride in methanolSample solution: Dissolve 100mg of Stearic Acid in aChange to read:small conical flask fitted with a suitable reflux attach-ment with 5mL of Boron trifluoride methanol consisting of Stearic (octadecanoic) acid (C18H36O2;Boil under reflux for 10 min.)

2 Add of heptaneMr, ) and palmitic (hexadecanoic) acid (C16H32O2;through the condenser, and boil again under reflux forMr, ) obtained from fats or oils of vegetable or10 min. Allow to cool. Add 20mL of a saturated solu-animal of sodium chloride. Shake, and allow the layers toContent:separate. Remove about 2mL of the organic layer, anddry it over of anhydrous sodium sulfate. of this solution with heptane to solution: Prepare as directed in the SampleStearic acid: Sum of thesolution using 50mg of USP Stearic Acid RS and 50mgcontents of Stearic acid and palmitic acids:of USP Palmitic Acid acid 50 NLT systemStearic acid: Sum of the(See Chromatography 621 , System Suitability.

3 Contents of Stearic and palmitic acids: NLTMode: GCStearic acid : Flame ionizationStearic acid: NLT Sum of the con-Column: 30-m fused silica coated with atents of Stearic acid and palmitic acids: layer of stationary phase G16 Stearic acid port: 220 : 260 [NOTE Stearic Acid labeled solely for external use is ex-Column: See Table from the requirement that it be prepared from ediblesources.] 1 IDENTIFICATIONHold Time A. It meets the requirements of the test for FreezingInitialTempera-Finalat to read:( )( /min)( )(min)70 702 B. ACID VALUE7052405 Light petroleum: Use a sample that has the followingproperties: a clear, colorless, liquid without fluores-Carrier gas: Helium, passed through a bed of molec-cence; practically insoluble in water; miscible with alco-ular sieve for drying, if necessaryhol; density at 20 about ; distillation rangeFlow rate: 120.

4 Water content NMT Injection volume: 1mLSample solution: Dissolve of Stearic Acid inSystem suitability50mL of a mixture of equal volumes of alcohol andSample: Standard solutionLight petroleum previously neutralized with N po-Suitability requirementstassium hydroxide or N sodium hydroxide, usingResolution: NLT between the methyl of phenolphthalein TS as indicator. If necessary,and methyl stearate peaks determined on sixheat to about 90 to dissolve the substance to standard deviation: NMT for theAnalysis: Titrate the Sample solution with N potas-methyl stearate and methyl palmitate peaks (from sixsium hydroxide or N sodium hydroxide until thereplicate injections of Sample solution); NMT color persists for at least 15 s.

5 When heating hasfor the ratio of the peak areas of methyl palmitate tobeen applied to aid dissolution, maintain the tempera-the peak areas of methyl stearate, from six replicateture at about 90 during the the acid value (IA) of the portion of StearicAnalysisAcid taken:Sample: Sample solutionCalculate the percentage of Stearic acid (C18H36O2) = (n/m) N MrsNF34the portion of Stearic Acid taken:n= amount of titrant used (mL)Result = (AS/AT) 100m= amount of Stearic Acid taken to prepare theSample solution (g)AS= peak area due to methyl stearateN= normality of the potassium hydroxide solutionAT= sum of the peak areas of all the fatty ether; boiling range 100 140 ; CAS 64742-49-0 from FisherScientific; catalog number AC23302-0025 is suitable.

6 2015 The United States Pharmacopeial ConventionAll Rights 6 Harmonization2 StearicOfficial May 1, 2016 Calculate the percentage of palmitic acid (C16H32O2) inChange to read:the portion of Palmitic Acid taken: ACIDITYR esult = (AP/AT) : of Stearic AcidsNF34 Analysis: Melt the ,sNF34 shake for 2 min withAP= peak area due to methyl palmitate10mL of hot carbon dioxide-free water, cool slowly,AT= sum of the peak areas of all the fatty acidand filter. To the filtrate add of methyl criteriaAcceptance criteria: No red color Stearic acid 50: of Stearic (octadeca- FREEZING POINT noic) acid (C18H36O2), and the sum of the Stearic acidApparatus: Consists of a test tube about 25mm inand palmitic acid is NLT and 150mm long placed inside a test tubeFor Stearic acid 70: of Stearic (octadeca-about 40mm in diameter and 160mm long.)

7 The innernoic) acid (C18H36O2), and the sum of the Stearic acidtube is closed by a stopper which carries a thermome-and palmitic acid is NLT about 175mm long and graduated in , fixed soFor Stearic acid 95: NLT of Stearic (octadeca-that the bulb is about 15mm above the bottom of thenoic) acid (C18H36O2), and the sum of the Stearic acidtube. The stopper has a hole allowing the passage ofand palmitic acid is NLT stem of a stirrer made from a glass rod or othersuitable material formed at one end into a loop ofIMPURITIES about 18mm overall diameter at right angles to the ON IGNITION 281 : NMT 4mg, determined onrod.

8 The inner tube with its jacket is supported cen-a 4-g portion ( )utrally in a 1-L beaker containing a suitable cooling liq-uid to within 20-mm of the top. A thermometer is sup-Delete the following:ported in the cooling bath. Place in the inner tubesufficient quantity of the liquid or previously melted . METALS, Method II 231 : NMT 10ppmu (Officialsubstance to be examined, to cover the thermometer1-Dec-2015)bulb, and determine the approximate freezing point bycooling TESTSA nalysis: Place the inner tube in a bath about 5 FATS AND FIXED OILS, Iodine Value 401 above the approximate freezing point until all but theSample: 1glast traces of crystals are melted.

9 Fill the beaker withAnalysis: Proceed as directed in Method I, except usewater or a saturated solution of sodium chloride; at a15mL of about 5 lower than the expected freezingAcceptance criteria: See Table , insert the inner tube into the outer tube, ensur-ing that some seed crystals are present, and stir thor-oughly until solidification takes place. Note the highestTable 2temperature observed during ValueAcceptance criteria: See Table acid 50 NMT acid 70 NMT 3 Stearic acid 95 NMT PointType( ) Stearic acid 5053 59 Change to read: Stearic acid 7057 64 Stearic acid 9564 69 OF SOLUTIONS tandard stock solution Y (yellow): of ferricchloride CS, of cobaltous chloride CS, andADDITIONAL of hydrochloric acid solution (10g/L) AND STORAGE.

10 Preserve in well-closed con-Standard stock solution BY (brownish-yellow) of ferric chloride CS, of cobaltous chlo-ride CS, of cupric sulfate CS, and ofhydrochloric acid solution (10g/L)Change to read:Standard solution Y: of Standard stock solutionY and of hydrochloric acid solution (10g/L) LABELING: it is for external use only, the labelingStandard solution BY: of Standard stock solu-so indicates. label states the type of steariction BY and of hydrochloric acid solution (10gacid (50, 70, or 95)./L) USP REFERENCE STANDARDS 11 Analysis: Heat Stearic Acid to 75.