100 90 80 � 70 3: 60 50 3: 40 "iii 30 20 10 0 2006 TRI/PRINCETON CONFERENCE 2 in 1 shampoo European shampoo Asian shampoo (w. dimethiconol) with dimethicone Asian hair Caucasian hair 1x treatment Asian shampoo Asian hair 3x treatment Shampoo with Hydr. didecene 1x treament Figure 5. Residual wet combing work of different shampoos. 449 n=10 Shampoo with Hydr. didecene 3x treatment treatments. Again, these performance properties are in good accordance with the high amount of dimethiconol adsorbed to the hair, without changing the level at repeated shampooing. In contrast, hair strands washed with the shampoo containing the hydro- genated didecene retain their volume even after repeated application. This can be ex- plained by the low levels of emollient found on the hair. ■ Shampoo with Hydrogenated didecene ♦ 2 in 1 shampoo with Dimethiconol 120 ' 100 C 80 t- II ' I - ' .. 60 t '' .. 40 20 n=10 0 . . . . . 0 3 5 Number of treatments Figure 6. Relative volume of hair strands after repeated treatment with a 2-in-l shampoo and with the shampoo containing hydrogenated didecene.

450 JOURNAL OF COSMETIC SCIENCE CONCLUSIONS Both investigated methods for the determination of silicones adsorbed on human hair from shampoos can be usefully applied for substantivity studies. While the main ad- vantage of the X-ray fluorescence method is the applicability to hair strands without extraction and the possibility to repeat treatments and measurements at the same hair strands, the benefit of ICP-OES of extracts is a smaller limit of detection and the fact that quantitative data can be obtained. In contrast, the faster XRF method delivers just semi-quantitative data which allow detecting build-up effects and removability of sili- cones. The analytical method developed for the quantification of the hydrogenated didecenes allows the quantification of low hydrocarbons levels in extracts of treated hair strands. It was demonstrated that a comparison of analytical data with results from performance measurements can be used to understand the effects of emollients on hair properties like conditioning and hair volume. The shampoo with hydrogenated didecene shows a good conditioning performance while retaining the volume of the shampooed hair strands. REFERENCES (1) E. G. Gooch and G. S. Kohl, Method to determine silicones on human hair by atomic absorption spectroscopy,]. Soc. Cosm. Chem., 39, 383-392 (1988). (2) S. R. Wendel and A. J. DiSapio, Organofunctional silicones for personal care applications, Cosmet. Toiletr., 98(5), 103-106 (1983). (3) H. M. Klimisch and G. S. Kohl, A quantitative diffuse reflectance method using Fourier transform infrared spectroscopy for determing siloxane deposition on keratin surfaces,]. Soc. Cosmet. Chem., 38, 247-262 (1987). (4) J. V. Gruber, B. R. Lamoureux, N. Joshi, and L. Moral, Influence of cationic polysaccharides on polydimethylsiloxane (PDMS) deposition onto keratin surfaces from a surfactant emulsified system, Colloidr Surf B., 19, 127-135 (2000). (5) K. Yahagi, Silicones as conditioning agents in shampoos,]. Soc. Cosmet. Chem., 43, 275-284 (1992).