THE EXTRACTION OF FATTY MATERIALS FROM HAIR CLIPPINGS 697 with distilled water to remove any trace of acid, dried in an oven at approx- imately 35øC, and then extracted with ether (25 cycles at 32-35øC). A further 1.5% of fatty material was obtained which was shown by ir analysis to be almost pure stearic acid. The calcium contents of the washings were also determined and when the calcium level was related to the weight of the hair sample taken, it was found that the calcium level (0.25% by weight) corresponded to that quoted (15) for hair as a whole (0.34%). This provides strong evidence for the calcium ion bridging mechanism. DISCUSSION AND CONCLUSIONS The purpose of this work has been to establish a method of extracting hair lipid under such conditions that the material obtained can be defined as the total fatty material present on the surface of the hair. For this reason a range of solvents of varying polarities was chosen and the effects of temperature and time of extraction were studied. A method for exhaustively extracting hair without damaging the structure has been established based on the sequential extraction with ether, methylene chloride and ethanol. Apart from the advantages to be gained in terms of total extraction time and convenience, the sequential extraction technique allows examination of the contribution of the different lipid fractions to the properties of the total combined lipid extract. This would be useful in distinguishing between hair lipids obtained from hair of different types or hair which had been subjected to different treatments. It is hoped to report such differences in subsequent papers. It is interesting to note that this study has also shown that the rate of extraction of ether- and alcohol-soluble material from hair is rather low (taking about 100 soxhlet cycles) which perhaps suggests that skin swabbing techniques also need to be examined carefully in terms of efficiency of extraction. The effect of extraction temperature on the material extracted from hair, particularly with ethanol, has also been shown to be extremely im- portant and the possibility exists that the same phenomena may occur with other solvents such as, for example, acetone. This work has also established the probable existence of a strongly ad- sorbed layer of material on the hair surface, consisting of high melting fatty acid possibly linked to the hair by calcium atom bridges. It is interesting to speculate on the effects of such material in the estimation of detergency

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