(lan' oh lin).
» Lanolin is the purified, wax-like substance from the wool of sheep, Ovis aries Linné (Fam. Bovidae), that has been cleaned, decolorized, and deodorized. It contains not more than 0.25 percent of water. It may contain not more than 0.02 percent 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.
USP Reference standards 11
USP Lanolin RS
Melting range, Class II 741: between 38 and 44, determined on a test specimen previously cooled to between 8 and 10.
Acidity 401 The free acids in 10.0 g require for neutralization not more than 2.0 mL of 0.10 N sodium hydroxide.
Alkalinity Dissolve 2.0 g in 10 mL of ether, and add 2 drops of phenolphthalein TS: the liquid is not colored red.
Water Dissolve about 25 g, accurately weighed, in 75 mL of a Mixed solvent consisting of 3 parts of chloroform and 2 parts of methanol, and dilute with Mixed solvent to 100.0 mL. Determine the water content of a 10.0-mL portion as directed under Water Determination, Method I 921. Perform a blank determination on 10.0 mL of Mixed solvent, and make any necessary correction. Not more than 0.25% is found.
Residue on ignition 281: not more than 0.1%.
Water-soluble acids and alkalies Warm 10.0 g with 50 mL of 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 A 10-mL portion of the solution from the test for Water-soluble acids and alkalies does not completely decolorize 50 µL of 0.10 N potassium permanganate within 10 minutes.
Chloride 221 Boil 20 mL of alcohol with 1.0 g of Lanolin under a reflux condenser, cool, add 1 mL of 2 N nitric acid, filter, and to the filtrate add 5 drops of a solution of silver nitrate in alcohol (1 in 50): any turbidity produced does not exceed that of a blank to which 0.50 mL of 0.020 N hydrochloric acid has been added (0.035%).
Ammonia Add 1 mL of 1 N sodium hydroxide to a 10-mL portion of the solution from the test for Water-soluble acids and alkalies, and boil: the vapors do not turn red litmus blue.
Iodine value 401: between 18 and 36, determined on a specimen of 780 to 820 mg.
Foreign substances [noteUse 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 100 mg of reference pesticide per L. [noteConcentrated stock solutions may be stored in the dark in glass-stoppered containers in a refrigerator at 2 to 5 for up to 1 year. Most pesticides may be dissolved directly in hexane; however, the hexachlorocyclohexane isomers and the DDT group 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 solutions quantitatively with hexane, and combine to obtain a composite Standard preparation having the concentrations indicated in Table 1. Store the composite Standard preparation in a glass-stoppered glass container in the dark at 2 to 5, and replace it every 2 months. [noteTwo or more separate composite Standard preparations, each preferably containing not more than 8 reference 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
eluantPrepare a mixture of methylene chloride and hexane (1:1).
apparatus The gel permeation chromatograph is equipped with a 25-mm × 50-cm column, packed with a slurry of 35 g of styrene-divinylbenzene copolymer beads compressed to a bed length of approximately 20 cm. The Eluant is pumped at a flow rate of about 5 mL per minute with an operating pressure of 8 to 11 psi. Set up the chromatograph, adjusting to discard the fraction eluting from 0 to 12 minutes, collect the fraction eluting from 12 to 32 minutes, and rinse for 2 minutes, discarding the rinse fraction.
elution of lanolinMelt a suitable quantity of Lanolin, and pass through a fluted filter paper into a container. Transfer about 6.0 g of the warm filtered Lanolin, accurately weighed, to a 50-mL volumetric flask. Dilute with Eluant to volume, mix, and filter. Transfer 5.0 mL of this solution to the gel permeation chromatographic column, and elute with Eluant. Collect 100 mL of the column effluent in tared beakers in 10-mL increments. Evaporate the solvent, cool, weigh the beakers and contents, and calculate the amount of lanolin eluted in each 10-mL increment. The column is suitable if not less than 96% of the lanolin elutes in the first 60 mL.
elution of pesticide from lanolinDissolve 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 0.6 µg, respectively. Transfer 5.0 mL of this solution to a 10-mL volumetric flask containing 1 g of USP Lanolin RS, dilute with methylene chloride to volume, and mix. Transfer 5 mL of this solution to the gel permeation chromatographic column, and elute with 160 mL of Eluant. Discard the first 60-mL fraction, and collect the next 100-mL fraction (from 60 to 160 mL). Transfer this collection fraction to a concentrator fitted with a graduated collection flask, add 50 mL of hexane, and concentrate by evaporation to 5 mL. Inject about 5 µL of this fraction into the chromatographs described under Chromatographic system I and 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 RS solution. Prepare a test solution by mixing hexane with the Standard solution (1:1). Inject 5 µL of the test solution into the chromatographs described under Chromatographic system I and 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 6 g of Lanolin, accurately weighed and previously melted to liquid form by heating on a hot water bath if necessary, to a 50-mL volumetric flask, dissolve in 25 mL of Eluant, dilute with Eluant to volume, mix, and filter. Transfer 5.0 mL of this solution to the column, and elute with 160 mL of Eluant. Discard the first 60-mL fraction, and collect the remaining fraction in a suitable evaporator. Concentrate by evaporation on a steam bath to about 3 mL, add about 50 mL of hexane, and evaporate again to remove all traces of methylene chloride, adjusting the volume with hexane to 3.0 mL.
Chromatographic system I (see Chromatography 621)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 G1 and 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. [noteThe initial temperature of the column may be adjusted so that the retention times of p,p¢-DDT and ethion are about 3.1 and 2.56, respectively, relative to chlorpyrifos. ] Helium is used as the carrier gas. The flow rate of about 25 mL per minute is adjusted so that the retention time of chlorpyrifos is about 4 minutes. The flow rate of the makeup gas, nitrogen, is about 40 minutes.
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 G3 and 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. [noteThe initial temperature of the column may be adjusted so that the retention time of ethion is about 3.36 relative to that of chlorpyrifos. ] Helium is used as the carrier gas at a flow rate of about 25 mL per minute, adjusted so that the retention time of chlorpyrifos is about 4 minutes. The flow rate of the makeup gas, nitrogen, is about 40 mL per minute. [noteDetermine the detector sensitivity for Chromatographic systems I and II: Select electrometer attenuation so that injection of 1.5 ng 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 [noteThe procedure described below is to be followed for Chromatographic systems I and II. ] Inject separately equal volumes (about 5 µL) of the appropriate composite Standard preparation and the Test preparation into 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 preparation obtained from each chromatographic system with those of the peaks that correspond to the retention times in the chromatogram of the appropriate composite Standard preparation obtained 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 rU and rS are the peak areas of the residue found in the Test preparation and the Standard preparation; respectively; C is the concentration, in mg per L, of the reference pesticide in the Standard preparation; and W is the weight, in g, of Lanolin taken: not more than 10 ppm of any individual specified residue is found, and the total of all specified residues found is not more than 40 ppm.
Petrolatum Heat about 3 g, accurately weighed, on a steam bath, with frequent stirring, until its weight loss is not less than its water content. Boil 40 mL of dehydrated alcohol with 500 mg of the dried lanolin so obtained: the solution is clear or not more than opalescent.
* Suitable materials may be obtained from either Chem Service, 660 Tower Lane, P.O. Box 3108, Westchester, PA 19381-3108 or Greyhound, 88 Grange Road West, Birkenhead, Merseyside, L43 4XF, England, U.K.
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USP35NF30 Page 3639