CASSIA HPTC IN CONDITIONING SHAMPOO 645 Figure 4. Cryo-SEM images: (a) Hair treated with clarifying shampoo, 10,000x magnification. (b) Hair treated with the cassia formula, 10,000x magnification. Deposition examples highlighted with circles. Table II Results of Polymer Analysis Following Extraction from Hair Sample Cassia formula Guar formula Clarifying formula µg polymer/g hair 294* (22%) 129 (19%) n.f. N = 3 samples percent relative standard deviation for each measurement is provided in parentheses. * p 0.05 (Student's t-test) compared with guar formula. percent transmittance curve, indicating that the cassia formula forms coacervates over a broader range of dilutions than the guar formula. The surface composition of the treated hair fibers was assessed using ToF-SIMS spec­ troscopy and imaging. ToF-SIMS is complementary to Cryo-SEM and extraction mea-

646 JOURNAL OF COSMETIC SCIENCE surements m that it provides a molecular image of the cassia polymer and anionic surfactant on the hair surface. Figure 5 shows representative positive-ion ToF-SIMS spectra from hair treated with the clarifying shampoo and the cassia formula. The spectrum of the hair treated with clarifying shampoo (Figure 5, top) was dominated by hydrocarbon (CxH y + ) and protein (CxH y Nz+) fragments many of the protein fragments were previously identified ( 13 ). After treatment of the hair with the cassia formula, several new secondary ions were observed that indicated the deposition of cassia HPTC onto the hair surface (Figure 5, bottom). Several of these secondary ions are identified in Table II. The CxH y Oz+ fragments are consistent with the polysaccharide structure of cassia and were also observed in a ToF-SIMS spectra of spin-cast films of cassia HPTC (data not shown). The additional C 3 H8N + (m/z = 58) fragment is due to the quaternary amine functionality in the cassia HPTC. Negative-ion-mode ToF-SIMS was used to characterize the surface composition of the treated hair fibers. Figure 6 shows representative negative-ion ToF-SIMS spectra from the same hair samples shown in Figure 5. The spectrum of the hair treated with clarifying shampoo (Figure 6, top) was dominated by protein fragments (CN-, CNO-, S0 3 - , HS0 4 -) in addition to alkyl sulfates and the covalently bound hair surface lipid 18-methyleicosanoic acid (18-MEA). Many of these ions have been previously identified in the work of Harvey et al. (14) and are also shown in Table III. Washing the hair with cassia formula increased the deposition of alkyl sulfate and alkyl ether sulfate anionic surfactants, indicating deposition of a cassia HPTC-surfactant coacervate onto the hair surface (Figure 6, bottom). The intensities of the secondary ions related to the hair surface (CN-, CNO-, 18-MEA) were reduced in this spectrum, further indicating that the cassia HPTC-surfactant coacervate covered the hair surface. 58 0 50 100 m/z 150 Hair treated with Clarifying Shampoo Hair treated with Shampoo containing Quaternized Cassia 200 250 Figure 5. Representative positive-ion ToF-SIMS spectra of hair treated with clarifying shampoo (top) and with the cassia formula (bottom).