Lanolin
»Lanolin is the purified,wax-like substance from the wool of sheep,Ovis ariesLinné(Fam.Bovidae),that has been cleaned,decolorized,and deodorized.It contains not more than 0.25percent of water.It may contain not more than 0.02percent of a suitable antioxidant.
Packaging and storage— Preserve in well-closed containers,preferably at controlled room temperature.
Labeling— The label states that it is not to be used undiluted.
Melting range,Class IIá741ñ: between 38and 44,determined on a test specimen previously cooled to between 8and 10.
Acidity á401ñ— The free acids in 10.0g require for neutralization not more than 2.0mLof 0.10Nsodium hydroxide.
Alkalinity— Dissolve 2.0g in 10mLof ether,and add 2drops of phenolphthalein TS:the liquid is not colored red.
Water— Dissolve about 25g,accurately weighed,in 75mLof a Mixed solventconsisting of 3parts of chloroform and 2parts of methanol,and dilute with Mixed solventto 100.0mL.Determine the water content of a 10.0-mLportion as directed under Water Determination,Method Iá921ñ.Perform a blank determination on 10.0mLof Mixed solvent,and make any necessary correction.Not more than 0.25%is found.
Residue on ignition á281ñ: not more than 0.1%.
Water-soluble acids and alkalies— Warm 10.0g with 50mLof water on a steam bath,constantly stirring the mixture until the Lanolin is melted:the fat separates completely on cooling,leaving the water layer nearly clear and neutral to litmus.Retain the water layer.
Water-soluble oxidizable substances— A10-mLportion of the solution from the test for Water-soluble acids and alkaliesdoes not completely decolorize 50µLof 0.10Npotassium permanganate within 10minutes.
Chloride á221ñ— Boil 20mLof alcohol with 1.0g of Lanolin under a reflux condenser,cool,add 1mLof 2Nnitric acid,filter,and to the filtrate add 5drops of a solution of silver nitrate in alcohol (1in 50):any turbidity produced does not exceed that of a blank to which 0.50mLof 0.020Nhydrochloric acid has been added (0.035%).
Ammonia— Add 1mLof 1Nsodium hydroxide to a 10-mLportion of the solution from the test for Water-soluble acids and alkalies,and boil:the vapors do not turn red litmus blue.
Iodine value á401ñ: between 18and 36,determined on a specimen of 780to 820mg.
Foreign substances— [NOTE—Use pesticide-free grade reagents and solvents throughout this test.Reference materials of pesticides for use in the Standard preparation may be obtained from any commercial source.*]
Standard stock solutions— Prepare stock solutions in hexane,each having a known concentration of 100mg of reference pesticide per L.[NOTE—Concentrated stock solutions may be stored in the dark in glass-stoppered containers in a refrigerator at 2to 5for up to 1year.Most pesticides may be dissolved directly in hexane;however,the hexachlorocyclohexane isomers and the DDTgroup of pesticides may require initial dissolution in the minimum volume of acetone followed by dilution with hexane to the specified concentration.]
Standard preparation— Dilute accurately measured volumes of the Standard stock solutionsquantitatively with hexane,and combine to obtain a composite Standard preparationhaving the concentrations indicated in Table 1.Store the composite Standard preparationin a glass-stoppered glass container in the dark at 2to 5,and replace it every 2months.[NOTE—Two or more separate composite Standard preparations,each preferably containing not more than 8reference pesticides,may be prepared if needed.Reference pesticides should be selected for composite Standard preparations on the basis that relative retention times (see Table 1)differ sufficiently so that peaks in chromatograms will be expected not to overlap,and they should be selected and combined appropriately for the chromatographic system and detector used.]
Gel permeation chromatography cleanup system—
ELUANT—Prepare a mixture of methylene chloride and hexane (1:1).
Table 1
Standard preparation
(Concentration
in µg per mL)		 Relative retention times
(relative to 1.0for
Chlorpyrifos)
Reference pesticide* Electron-
capture detector		 Flame-
photometric detector		 System I System II
Tetrachloronitrobenzene [TCBN] 0.05 — 0.29 0.24
alpha Hexachlorocyclohexane (alpha BHC) 0.05 — 0.40 0.35
beta Hexachlorocyclohexane (beta BHC) 0.30 — 0.43 0.56
Hexachlorobenzene (HCB) 0.05 — 0.45 0.33
gamma Hexachlorocyclohexane (Lindane) 0.05 — 0.48 0.41
Propetamphos — 0.30 0.48 0.42
Diazinon — 0.20 0.52 0.40
Dichlofenthion 0.10 0.20 0.67 0.56
Ronnel 0.30 0.40 0.81 0.66
Heptachlor 0.10 — 0.83 0.60
Malathion — 0.40 0.91 1.05
Chlorpyrifos 0.30 0.30 1.00 1.00
Aldrin 0.20 — 1.05 0.76
Pirimiphos Ethyl — 0.40 1.14 1.14
Chlorfenvinphos Z 0.40 0.40 1.17 1.40
Heptachlor epoxide 0.20 — 1.29 1.17
Chlorfenvinphos E 0.40 0.50 1.30 1.51
Bromophos ethyl 0.40 0.50 1.51 1.45
1,1¢-dichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethene (o,p-DDE) 0.30 — 1.55 1.51
1,1¢-dichloro-2-(4-chlorophenyl)-2-(4-chlorophenyl)ethene (p,p-DDE) 0.30 — 1.88 1.86
Stirophos 0.60 0.80 1.58 1.97
alpha Endosulfan 0.40 — 1.63 1.47
1,1¢-dichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethane (o,p-TDE) 0.40 — 1.90 2.19
Dieldrin 0.30 — 1.91 1.84
Endrin 0.40 — 2.13 2.29
beta Endosulfan 0.40 — 2.19 2.77
1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (p,p-TDE) 0.40 — 2.41 2.87
1,1,1-trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethane (o,p-DDT) 0.40 — 2.55 2.70
Ethion 1.00 0.40 2.56 3.36
Carbophenothion 0.80 1.00 2.94 3.70
1,1,1-trichloro-2,2-bix(4-chlorophenyl)ethane (p,p¢-DDT) 0.50 — 3.13 3.50
Methoxychlor 0.60 — 4.70 7.20
Carbophenothion Sulfone 5.00 — 5.10 9.20
Carbophenothion Sulfoxide 5.00 — 5.40 10.00
*  Suitable materials may be obtained from either Chem Service,660Tower Lane,P.O.Box 3108,Westchester,PA19381-3108or Greyhound,88Grange Road West,Birkenhead,Merseyside,L434XF,England U.K.
APPARATUS— The gel permeation chromatograph is equipped with a 25-mm ×50-cm column,packed with a slurry of 35g of styrene-divinylbenzene copolymer beads compressed to a bed length of approximately 20cm.The Eluantis pumped at a flow rate of about 5mLper minute with an operating pressure of 8to 11psi.Set up the chromatograph,adjusting to discard the fraction eluting from 0to 12minutes,collect the fraction eluting from 12to 32minutes,and rinse for 2minutes,discarding the rinse fraction.
System suitability—
ELUTION OF LANOLIN—Melt a suitable quantity of Lanolin,and pass through a fluted filter paper into a container.Transfer about 6.0g of the warm filtered Lanolin,accurately weighed,to a 50-mLvolumetric flask.Dilute with Eluantto volume,mix,and filter.Transfer 5.0mLof this solution to the gel permeation chromatographic column,and elute with Eluant.Collect 100mLof the column effluent in tared beakers in 10-mLincrements.Evaporate the solvent,cool,weigh the beakers and contents,and calculate the amount of lanolin eluted in each 10-mLincrement.The column is suitable if not less than 96%of the lanolin elutes in the first 60mL.
ELUTION OF PESTICIDE FROM LANOLIN—Dissolve suitable quantities of diazinon,diclofenthion,bromophos ethyl,lindane,and dieldrin in hexane to obtain a Standard solution having concentrations,in each mL,of 0.4,0.4,1.0,0.1,and 0.6µg,respectively.Transfer 5.0mLof this solution to a 10-mLvolumetric flask containing 1g of USP Lanolin RS,dilute with methylene chloride to volume,and mix.Transfer 5mLof this solution to the gel permeation chromatographic column,and elute with 160mLof Eluant.Discard the first 60-mLfraction,and collect the next 100-mLfraction (from 60to 160mL).Transfer this collection fraction to a concentrator fitted with a graduated collection flask,add 50mLof hexane,and concentrate by evaporation to 5mL.Inject about 5µLof this fraction into the chromatographs described under Chromatographic system Iand Chromatographic system II,record the chromatograms,and measure the heights of the peaks obtained from the five pesticides in the Standard solution.Calculate the recoveries of each of the five pesticides used in the fortified USP Lanolin RSsolution.Prepare a test solution by mixing hexane with the Standard solution (1:1).Inject 5µLof the test solution into the chromatographs described under Chromatographic system Iand Chromatographic system II,record the chromatograms,and measure the peak heights of the five pesticides in the chromatogram of the test solution.Compare the peak heights obtained from the fraction of the Standard solution to the peak heights of the corresponding pesticides obtained from the test solution:not less than 85%of the added amounts of each of the five pesticides is recovered.
Test preparation— Transfer about 6g of Lanolin,accurately weighed and previously melted to liquid form by heating on a hot water bath if necessary,to a 50-mLvolumetric flask,dissolve in 25mLof Eluant,dilute with Eluantto volume,mix,and filter.Transfer 5.0mLof this solution to the column,and elute with 160mLof Eluant.Discard the first 60-mLfraction,and collect the remaining fraction in a suitable evaporator.Concentrate by evaporation on a steam bath to about 3mL,add about 50mLof hexane,and evaporate again to remove all traces of methylene chloride,adjusting the volume with hexane to 3.0mL.
Chromatographic system I (see Chromatography á621ñ)—The gas chromatograph is equipped with an electron-capture detector and a 0.53-mm ×30-m fused silica capillary column bonded with a 1.5-µm layer of phase G1and a 0.53-mm ×6-m fused silica uncoated guard column connected to a modified packed column-type injector system.The column temperature is maintained at 200.[NOTE—The initial temperature of the column may be adjusted so that the retention times of p,p¢-DDTand ethion are about 3.1and 2.56,respectively,relative to chlorpyrifos.]Helium is used as the carrier gas.The flow rate of about 25mLper minute is adjusted so that the retention time of chlorpyrifos is about 4minutes.The flow rate of the makeup gas,nitrogen,is about 40minutes.
Chromatographic system II— The gas chromatograph is equipped with a flame-photometric detector and a 0.53-mm ×30-m fused silica capillary column bonded with a 1.0-µm layer of phase G3and a 0.53-mm ×6-m fused silica uncoated guard column connected to a modified packed column type injector system.The column temperature is maintained at 200.[NOTE—The initial temperature of the column may be adjusted so that the retention time of ethion is about 3.36relative to that of chlorpyrifos.]Helium is used as the carrier gas at a flow rate of about 25mLper minute,adjusted so that the retention time of chlorpyrifos is about 4minutes.The flow rate of the makeup gas,nitrogen,is about 40mLper minute.[NOTE—Determine the detector sensitivity for Chromatographic systems Iand II:Select electrometer attenuation so that injection of 1.5ng of chlorpyrifos produces 50%full-scale deflection on a recorder or printer-plotter.If these detector conditions are outside the linear range of the detector,adjust to the linear range,and record the quantity,in ng,of chlorpyrifos producing 50%full-scale deflection at these conditions.]
Procedure— [NOTE—The procedure described below is to be followed for Chromatographic systems Iand II.]Inject separately equal volumes (about 5µL)of the appropriate composite Standard preparationand the Test preparationinto the gas chromatograph,record the chromatograms,and measure the areas of all the peaks observed in the chromatograms.Compare the peak areas of any of the pesticide residues in the chromatogram of the Test preparationobtained from each chromatographic system with those of the peaks that correspond to the retention times in the chromatogram of the appropriate composite Standard preparationobtained from each of the corresponding chromatographic systems.Calculate the quantity,in ppm,of the individual specified residue found in the sample taken by the formula:
30(C/W)(rU/rS),
in which rUand rSare the peak areas of the residue found in the Test preparationand the Standard preparation;respectively;Cis the concentration,in mg per L,of the reference pesticide in the Standard preparation;and Wis the weight,in g,of Lanolin taken:not more than 10ppm of any individual specified residue is found,and the total of all specified residues found is not more than 40ppm.
Petrolatum— Heat about 3g,accurately weighed,on a steam bath,with frequent stirring,until its weight loss is not less than its water content.Boil 40mLof dehydrated alcohol with 500mg of the dried lanolin so obtained:the solution is clear or not more than opalescent.
*  Suitable materials may be obtained from either Chem Service,660Tower Lane,P.O.Box 3108,Westchester,PA19381-3108or Greyhound,88Grange Road West,Birkenhead,Merseyside,L434XF,England,U.K.
Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 1107
Phone Number:1-301-816-8389
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