QUANTIFICATION OF ULTRASTRUCTURAL CHANGES IN HAIR 59 Table III Ultrastructural Changes in Weathered Hair as a Result of Shampooing* Total Number Mean Area Treatment % Voids of Voids of Voids (ptm 2) Non-Shampooed 1.05 Cortex [Shampooed 0.903 -Shampooed 0.412 Cuticle LShampooed 0. 725 76 0.176 67 0.187 35 0.0358 57 0.0448 * Each value represents the median of 40 measurements. weathering is reflected in ultrastructural changes in the cuticle and cortex of hair fiber cross sections. In addition, the impact of chronic shampooing on hair fiber ultrastruc- ture is limited to the cuticle region of weathered hair fibers. The use of electron microscopy to assess subtle changes in fiber structure requires that a representative sampling be made and a sufficiently large set of micrographs be re- viewed. Image analysis allows a more objective quantitative approach to electron mi- crograph interpretation and allows one to analytically verify observed ultrastructural effects. ACKNOWLEDGEMENTS We gratefully acknowledge the contributions of our statistician Steve Pozzi, Carrie Ackerman for computer programming assistance, Don Coble for providing the trans- mission electron micrograph, and Dr. Miklos Breuer for helpful discussions and con- tinued support. REFERENCES (1) G. E. Rogers, Electron microscope studies of wool and hair, Ann. N.Y. Acad. Sci., 83, 378-399 (1959). (2) R. D. B. Fraser, T. P. MacRae, and G. E. Rogers, Keratins, (Charles C. Thomas, Illinois, 1972), p 70. (3) J. D. Leeder, D. G. Bishop, and L. N. Jones, Internal lipids of wool fibers, Textile Res. J., 402- 407 (July 1983). (4) J. A. Swift and B. Bews, The chemistry of human hair cuticle. Part II: The isolation and amino acid analysis of the cell membranes and A-layer, J. Soc. Cosmet. Chem., 25, 355-366 (1974). (5) J. H. Bradbury, J. D. Leeder, and I. C. Watt, The cell membrane complex of wool, Appl. Polymer Syrup., 18, 227-235 (1971). (6) J. A. Swift and B. Bews, The chemistry of human hair cuticle. Part III: The isolated and amino acid analysis of various subfractions of the cuticle obtained by pronase and trypsin digestion. J. Soc. Cosmet. Chem., 27, 289-300 (1976). (7) G. Mahrle, W. Sterry, and C. E. Orfanos, "The Use of Scanning-Electron Microscopy to Assess Damage of Hair," in Hair Research, C. E. Orfanos, W. Montagna, and G. St•ttgen, Eds. (Springer- Verlag, New York, 1981), pp 524-528. (8) I. J. Kaplin, A. Schwan, and H. Zahn, Effects of cosmetic treatments on the ultrastructure of hair. Cosmetics and Toiletries, 97, 22-26 (1982).

j. Soc. Cosmet. Chem., 36, 61-74 (January/February 1985) Quantitative Fourier transform infrared spectroscopy of oxidized hair JOHN STRASSBURGER, Gillette Research Institute, 1413 Research Blvd., Rockville, MD 20850, and MIKLOS M. BREUER, Personal Care Division, Gillette Company, Gillette Park, Boston, MA 02106. Received October 31, 1984. Presented at the Society of Cosmetic Chemists Annual Scientific Meeting, New York, December 6-7, 1984. Synopsis Oxidative hair damage was measured with a Fourier transform infrared spectrometer using a high pressure diamond anvil cell. Disulfide bond cleavage by bleaching or thioglycollate waving was distinguished from that caused by bisulfite treatment. Oxidative damage was quantified by normalizing the S = O band intensity (near 1040 cm-•) against various keratin band intensities. The intensity ratio producing the most precise quantitative results for replicate determinations was established. Intensities obtained after spectral subtraction were found to give the best results. The reproducibility of the measurements was also established. Oxidative damage was measured on a variety of hair tresses that were subjected to various cosmetic treatments (e.g. bleaching, waving) and environmental weathering. The technique was found to give reproducible results and was capable of determining absolute levels of sulfonic acid in hair. Further- more, the method can also be used for measuring sulfonate (- SO•) and thiosulfonate (- S- SO i) group concentrations in hair. INTRODUCTION Evaluation of hair damage is a problem that preoccupies cosmetic chemists. The problem is particularly important in judging the performance of hair bleaches, hair dyes, and permanent waving lotions, which all include an oxidation step during their application. In addition, hair also undergoes natural oxidative degradation processes (weathering) owing to its exposure to sun and atmospheric oxygen. Prevention, or at least the slowing down, of weathering of hair is a major concern of cosmetic chemistry. Methods capable of measuring oxidative hair damage are of great interest to the hair care industry. The present paper describes a new method for measuring oxidative hair damage based on Fourier transform infrared spectroscopy (FTIR). A number of investigators (1-5) have studied keratin oxidation using infrared spectroscopy. Most have found that per- oxide oxidation leads to major infrared absorption bands at 1040 cm- • and 1175 cm- • The assignment of these two bands as sulfonate linkages from cysteic acid residues seems well established (6,7). Cysteic acid residues arise from disulfide bond fission of cystine, the most abundant amino acid found in hair (8,9). The use of the intensity of the S -- O band at 1040 cm- 1 for quantifying oxidative hair 61