324 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS O • 4.-., ,to O •+ 0(3 O O 4.-., 4.-.,

HAIR OILINESS 325 contribute to the sensory impression of hair, and prior to the isolation of the internal lipids, they have to be removed together with the external sebum by successive extractions with water-saturated ether as described before and ethereal HC1. In Table VI the liquid chromatographic results of a dry and an oily hair sample are compiled. In both cases our standard extraction procedure for external lipids with boiling water-saturated ether had yielded only little more than half of the total lipids present on and in the hair. The additional extraction with ether/hydrochloric acid at room temperature removed a considerable quantity of free fatty acids (plus Ca 2+ and Mg 2+) and some other lipids from the only hair and a minor amount from the dry sample.* However, even after these rather drastic extraction conditions the oily hair had still retained approximately 20% of its total lipid content, the dry hair approximately 35%. These were liberated only after enzymatic digestion of the hair keratin. This observation supports the assumption that these lipids are actually locked up in the hair. Therefore, the term "internal lipids" seems to be justified. Concerning the origin of these lipids it was interesting to observe that the wax ester(WE)/cholesterol ester(CE) fraction consists mainly of CE, whereas the corre- sponding fraction of the external lipids always contains 95-98% WE. According to references 16, 18-20, CE are structural lipids and are not synthesized in the sebaceous gland. On the other hand, the content of triglycerides and squalene prove that internal sebum at least partly includes sebaceous lipids which have either diffused into or associated within the hair. In the light of other results obtained in our laboratory (21) on migration of lipids through synthetic polymers, it may be expected that the hair keratin does discriminate between different lipid species w.r.t. permeability with the effect that internal sebum differs in composition from external sebum, although both are of the same origin. ACKNOWLEDGEMENT The authors are indebted to Mrs. U. Siebert for expert assistance. REFERENCES (1) D. A. Shaw, Hair lipid and surfactants. Extraction of lipid by surfactants and lack of effect of shampooing on rate of re-fatting of hair, Int. J. Cosmet. Sci., 1,317 (1979). (2) G. Hopf and A. Winkler, Untersuchungen iiber die Spreitwirkung des Hauttalges, Fette, Seifen, Anstrichm., 61,974 (1959). (3) F. Neuwald, K. E. Fetting, and A. Szakall, Untersuchungen iiber die Fi/higkeit der Spreitung yon Lipoiden und der Permeation yon Wasserdampf durch die lebende Haut, Fette, Seifen, Anstrichm, 64, 465 (1962). (4) H. Eberhardt, The regulation of sebum excreti.9n in man, Arch. Dermatol. Forsch., 251,155 (1974). (5) M. Gloor, J. Breitinger, and H. C. Friederich, Uber die Zusammensetzung der Hautoberfli/chenlipide bei Seborrhea oleosa und Seborrhea sicca, Arch. Dermatol. Forsch., 247, 59 (1973). (6) K. Aitzetmiiller and J. Koch, Liquid chromatographic analysis of sebum lipids and other lipids of medical interest,J. Chrom., 145,195 (1978). (7) J. Swift and B. Bews, The isolation of membranes from keratin fibres with papain and dithiothreitol,J. Text. Inst., 65,222 (1974). *This coincidence is accidental. In part II of this paper it will be demonstrated that the quantity of Ca- and Mg-carboxylates on a hair example does not correlate with its degree of oiliness.