THE WATER ABSORPTION PROPERTIES OF LANOLIN 433 grease sample in a sufficiently pure state for qualitative identification by ir spectroscopy, at least for the five named detergents, the spectra of which show distinguishing characteristics. After the second dean-up, as much as possible of the precipitate is scraped out of the filter crucible and dissolved in $ ml sodium hydroxide solution (10% w/v) + 1 ml sodium sulphate solution (10% w/v). The solution is shaken with 25 ml trichloroethylene and allowed to separate into two layers, the lower layer containing the detergent being filtered and con- centrated by evaporation. The concentrate is transferred gradually to a 0.05 mm nominal width silver chloride cell from which the trichloroethylene is allowed to evaporate. The open cell is heated in the oven at 105øt2 for 5 min to ensure removal of residual solvent, and then the spectrum is re- NONIDET P40 A pure B recovered •400 1200 1000 800 Wave. number, cm -1 Figure 5. Superimposed ir spectra of pure and recovered ethoxylated alkylphenol detergent

434 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS corded against a silver chloride reference. Up to a frequency of 1 600 cm- • the spectra of recovered detergents are practically indistinguishable from those of the corresponding pure detergents, as exemplified by the super- imposed spectra shown in Figs. 5 and 6. NONIDET SH IO0 A pure B recovered 1600 I I I I 1400 1200 1000 800 Wavenumber, cm -1 Figure 6. Superimposed ir spectra of pure and recovered ethoxylated linear alcohol detergent REMOVAL OF DETERGENT FROM LANOLIN It has been found possible to remove nonionic polyoxyethylene deter- gents from lanolin or wool grease by extraction from the molten lanolin with hot aqueous isopropanol or ethanol, 45}/0 v/v being the optimum concen- tration of alcohol for bulk processing. Using equal volumes of lanolin and 45% isopropanol at 60øC the partition coefficient for the detergent has been