698 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS efficiency of shampoos, since most techniques of detergency evaluation include solvent extraction of hair before and after shampooing. It is con- ceivable that, depending on the pH of the shampoo and rinsing solutions and the hardness of the water used, the extractable lipid material on the hair could either increase after shampooing if the pH was acid, and/or decrease after rinsing in hard water owing to the formation of calcium soaps which are rendered non-extractable. The former effect could give rise to abnorm- ally low values of detergency efficiency while the latter effect would indicate particularly high values of lipid removal by shampoos. (Received: 18th February 1971) REFERENCES (1) Strauss, J. S. and Pochi, P. E., The quautitative gravimetric determination of sebum. f. Invest. Derrnatol., 3{i 285 (1961). (2) Hodgson-Jones, I. S. and WheatIcy, V. R. Methods of collection and extraction of small amounts of sebum. Biochem. J., õ•. 460 (1952). (3) Kligman, A.M. and Shelley, x•V. B. An investigation of the biology of the human seba- ceous gland. J. Invest. Dermatol., 30 99 (1958). (4) •Vheatley, V. R. Problems in the aualysis of sebum, advances in biology of skin, Vol. 4, Pergamon Press (1963) p.135. (5) Harry, R. G. The principles and practice of modern cosmetics, Vol. 1, Leonard Hill (Books) Ltd., London 1962, p.383. (6) Nitechke, G. Fette Seifen Anstrichrnittd, 66 (9) 678 (1964). (7) Ester, V. C., Henkin, H. and Longfellow, J. D. The use of hair clippings in the evaluation of shampoos. Proc. Sci. Sect. Toilet Goods Assoc., •.0 8 (1953). (8) Barnett, G. and Powers, D. H. A quantitative method for the evaluation and study of shampoos. J. Soc. Cosmet. Chem., •. 219 (1951). {9) Brasch, S. V. and Amoore, J. A. The quantitative estimation of the detergency and allied properties of shampoos in practice. J. Soc. Cosmet. Chem., 18 651 (1967). (10) Brasch, S. V. and Amoore, J. A. The effect of shampooing a solvent extractable material on hair. J. Soc. Cos•net Chem., 18 31 (1967). (11) Lewis, C., Hayward, B. J. and McKenna, R. M. B. Saturated hydrocarbons in skin surface lipids. Brit. J. Dermatol., 77 (6) (1965). (12) Nicolaides, N. Advances in biology of skin, Volume 4, Pergamon Press, 1963, p.167. (13) Swift, J. A. and Holmes, A. x,V. Degradation of human hair by papain. Part III. Some electron microscope observations. Teztile Res. J., 3õ 1014 (1965). (14) Leon, N.H. and Holmes, A. W. Personal communication, (15) Coleman, R. F., Cripps, F. H., Stimson, A. and Scott, H. D. The determination of trace elements in human hair by neutron activation and the application to forensic science. AWRE Report No. 0-86/66 (1967). DISCUSSION MR. M. G. DEN.•V.•RRE: Do you suspect that this stearic acid comes from external sources such as from washing, rather than being part of the skin lipids? M•. Cu•¾: This stearic acid was obtained by solvent extraction of clean hair that had been soaked in a dilute acid solution after previous exhaustive extraction. I believe that the stearic acid was originally in the form of calcium and magnesium stearates that are extremely difficult to remove from the hair by either washing or solvent extraction. The source of the stearic acid is probably sebum, and the calcium

THE EXTRACTION OF FATTY MATERIALS FROM HAIR CLIPPINGS 699 and magnesium stearates are formed from the interaction of calcium and magnesium ions from the water, with free fatty acids in the sebum during the washing and rinsing stages. Even if shampoos removed all hair lipid from hair, and we knoxv they do not, there would still be a residue of calcium and magnesium salts on the hair after drying which would react with freshly generated hair lipid. As a result, and since almost all methods of assessing shampoo detergency are based on solvent extraction techniques, it follows that large errors can be made in estimating detergency efficiency depending on the pH of the wash solutions and the hardness of the water. A shampoo with an acid pH can liberate "extra" fatty acid, whilst washing in hard water can insolubilise fatty acid not removed by the shampoo. This is a separate phenomena to the well known adverse effects of calcium and magnesium ions on detergents. MR. M. G. OENAVARRE: That is very interesting. Do you not consider that this is actually fat that is tied into the keratin molecule as a lipoprotein? MR. CURRY: Some of the material present in the initial high temperature extracted alcohol-soluble fractions described earlier is undoubtedly intracellular material such as phospho-lipids, lipoproteins, etc. However, after the hair has been exhaustively extracted with alcohol, methylene chloride and ether and allowed to stand for several days, a further amount of ether soluble material is extractable. I believe that this material is free fatty acid from calcium and magnesium stearates on the surface of the hair which are slowly hydrolysing.