Sodium Lauryl Sulfate

Sulfuric acid monododecyl ester sodium salt.
Sodium monododecyl sulfate [151-21-3].
»Sodium Lauryl Sulfate is a mixture of sodium alkyl sulfates consisting chiefly of sodium lauryl sulfate [CH3(CH2)10CH2OSO3Na].The combined content of sodium chloride and sodium sulfate is not more than 8.0percent.
Packaging and storage— Preserve in well-closed containers.
Identification—
A: Ignite about 500mg at 800until the carbon is consumed:the residue dissolved in 10mLof water responds to the tests for Sodium á191ñ.
B: Asolution (1in 10)after acidification with hydrochloric acid and gentle boiling for 20minutes,responds to the tests for Sulfate á191ñ.
Alkalinity— Dissolve 1.0g in 100mLof water,add phenol red TS,and titrate with 0.10Nhydrochloric acid:not more than 0.60mLis required for neutralization.
Sodium chloride— Dissolve about 5g,accurately weighed,in about 50mLof water.Neutralize the solution with 0.8Nnitric acid,using litmus paper as the indicator,add 2mLof potassium chromate TS,and titrate with 0.1Nsilver nitrate VS.Each mLof 0.1Nsilver nitrate is equivalent to 5.844mg of NaCl.
Sodium sulfate—
Lead nitrate solution— Dissolve 33.1g of lead nitrate in water to make 1000mL.
Procedure— Transfer about 1g of Sodium Lauryl Sulfate,accurately weighed,to a 250-mLbeaker,add 35mLof water,and warm to dissolve.To the warm solution add 2.0mLof 1Nnitric acid,mix,and add 50mLof alcohol.Heat the solution to boiling,and slowly add 10mLof Lead nitrate solution,with stirring.Cover the beaker,simmer for 5minutes,and allow to settle.If the supernatant is hazy,allow to stand for 10minutes,heat to boiling,and allow to settle.When the solution is almost to a boiling point,decant as much liquid as possible through a 9-cm filter paper (Whatman No.41or equivalent).Wash four times by decantation,each time using 50mLof 50percent alcohol,and bring the mixture to a boil.Finally,transfer the filter paper to the original beaker,and immediately add 30mLof water,20.0mLof 0.05Medetate disodium VS,and 1mLof ammonia-ammonium chloride buffer TS.Warm to dissolve the precipitate,add 0.2mLof eriochrome black TSand titrate with 0.05Mzinc sulfate VS.Each mLof 0.05Medetate disodium is equivalent to 7.102mg of Na2SO4.
Unsulfated alcohols— Dissolve about 10g,accurately weighed,in 100mLof water,and add 100mLof alcohol.Transfer the solution to a separator,and extract with three 50-mLportions of solvent hexane.If an emulsion forms,sodium chloride may be added to promote separation of the two layers.Wash the combined solvent hexane extracts with three 50-mLportions of water,and dry with anhydrous sodium sulfate.Filter the solvent hexane extract into a tared beaker,evaporate on a steam bath until the odor of solvent hexane no longer is perceptible,dry the residue at 105for 30minutes,cool,and weigh.The weight of the residue is not more than 4.0%of the weight of the Sodium Lauryl Sulfate taken.
Total alcohols— Transfer about 5g,accurately weighed,to an 800-mL Kjeldahl flask,and add 150mLof water,50mLof hydrochloric acid,and a few boiling chips.Attach a reflux condenser to the Kjeldahl flask,heat carefully to avoid excessive frothing,and then boil for about 4hours.Cool the flask,rinse the condenser with ether,collecting the ether in the flask,and transfer the contents to a 500-mLseparator,rinsing the flask twice with ether and adding the washings to the separator.Extract the solution with two 75-mLportions of ether,evaporate the combined ether extracts in a tared beaker on a steam bath,dry the residue at 105for 30minutes,cool,and weigh.The residue represents the total alcohols,and is not less than 59.0%of the weight of Sodium Lauryl Sulfate taken.
Auxiliary Information— Staff Liaison:Justin Lane,B.S.,Scientific Associate
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3078
Phone Number:1-301-816-8323