SORPTION OF PEPTIDES BY HAIR 601 Percent Peptide Sorbed 1,0 I I I I I I I I I I 0.8-- -- 0.6 0.4 0.2 m,n in hair 0 I I I I I I I I I I 2 3 4 s 6 7 8 9 lo ll 2 pH Figure 1. Sorption of peptides from solutions of different pH values by peroxide-damaged hair. (The curves are identified by the time the hair was bleached) Cold wave treatments were carried out in 5% ammonium thio- glycolate at pH 9.3 for neutralization 3/•/o sodium bromate was used for a period of five minutes. In all cases, at the completion of a given treatment or combination of treatments, the samples were rinsed in running tap water for two to three minutes, blotted, dried, and finally immersed in 5• peptide* solutions which had been adjusted by the addition of dilute HC1 or NaOH to specific pH values from pH 1 to 12. The strands were kept in the peptide solution for 15 minutes, after which they were rinsed by immersion in distilled water for twenty-five minutes, blotted, and dried. The sorbed peptide was measured by means of the hydroxyproline analysis. The treatment period of fifteen minutes was chosen since it has been shown (2) that there is rapid sorption of peptide in fifteen minutes, followed by a much slower sorption rate up to a period of * Wilson & Co., Inc., Substantive Proteins WSP-X250.

6O2 JOURNAL OF THE SOCIETY OF COSiViETIC CHEiViISTS Figure 2. Percent Peptide Sorbed 0.,5- 0.4 0.3 30 min Vir• 0.1 o •'•i I • • I I I I 1 2 3 4 5 8 9 10 11 2 6 7 Sorption of peptides from solutions of different pH values by peroxide-damaged hair. (The curves are identified by the time the hair was bleached) one hour. In some instances in which treatment at pH values of 1 to 4 did not appear to show differences, the strands were treated with peptide solutions from pH 4 to 12. Effect of Bleaching on Peptide Sorption at Various pH Levels The curves in Fig. 1 demonstrate the shift in the pH of maximum peptide sorption with extent of bleaching. The curve for unbleached virgin hair shows little peptide sorption from solutions at pH 1 to .5, after which a gradual increase occurs to a maximum at pH 8 to 11 with a slight drop at pH 12. After a five minute bleach period, the maximum appears at pH 8-10 and after ten minutes of bleaching, the maximum drops to 7 and remains at pH 6-7 thereafter, even after bleaching periods of sixteen hours. Sorption increases considerably after only five to ten minutes of bleaching, but for somewhat longer periods of time (fifteen to thirty minutes) there is very little further increase in peptide sorption, as shown on Fig. 2. After one hour of bleaching an actual decrease in