370 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II Cystine Content and Liquid Retention of Bleached* Hair No. of Cystine Content Treatments (ix mole/g hair) Liquid Retention (%) 0 647 37.5 1 553 41.3 3 489 45.3 5 450 52.8 * Hair was bleached in alkaline hydrogen peroxide solution. reverse reaction rate constants were also determined from the kinetic data using eq. 12. Hair fiber bleaching by peroxide oxidation was accompanied by a decrease in disulfide bonds (from 647 to 450 p• mole/g of hair) and an increase in liquid retention (from 38 to 53%). The data indicate that the disulfide analysis prior to and after oxidative treatment can be used to determine the decrease in cystine content caused by the treatment. 60 50 40 30 i 4 $ CYSTINE CONTENT (x 10 -4 mol©/g HAIR) Figure 4. The relationship between liquid retention and the cystine content of bleached hair.

HAIR BIS-DINITROPHENYL CYSTINE INTERCHANGE 371 ACKNOWLEDGEMENTS The authors thank Ms. I. Cushman for preparing hair samples and determining liquid retention values and Mr. S. Pozzi for statistical evaluation of data. REFERENCES (1) F. Sanger, A disulfide interchange reaction, Nature, 171, 1025-1026 (1953). (2) A. P. Ryle and F. Sanger, Disulfide interchange reactions, Blochem. J., 60, 535-540 (1955). (3) R. E. Benesch and R. Benesch, The mechanism of disulfide interchange in acid solution: Role of sulfonium ions, J. Am. Chem. Soc., 80, 1666-1669 (1958). (4) A. N. Glazer and E. L. Smith, Estimation of cystine and cysteine in proteins by disulfide interchange reaction, J. Bio/. Chem., 236, 416-421 (1961). (5) L. J. Wolfram "The Reactivity of Human Hair. A Review," in Hair Research, C. E. Orfanos, W. Montagna, and G. Stuttgen, Eds. (Springer-Verlag, New York, 1981) p 479. (6) C. R. Robbins and M. K. Bahl, Analysis of hair by electron spectroscopy for chemical analysis, J. Soc. Cos. Chem., 35, 379-390 (1984). (7) H. Alter and M. Bit-Alkhas, Infrared analysis of oxidized keratin, Text. Res. J., 39, 479-481 (1969). (8) J. Nachtigal and C. R. Robbins, Intermediate oxidation products of cystine in oxidized hair, Text. Res. J., 40, 454-457 (1970). (9) L. J. Wolfram, K. Hall, and I. Hui, The mechanism of hair bleaching, J. Soc. Cosmet. Chem., 21, 875-900 (1970).