POLYMERS AND LIPIDS ON SKIN BY ESCA 305 Table IX ESCA Analysis of Stratum Corneum Treated With Emollients Under Modified Conditions Castor oil: 5-minute SDS post-treatment Treatment C O N S C - C/C - O A 80.0 13.7 1.8 0.4 7.6 B 77.8 14.2 4.3 0.8 5.5 C 79.7 14.8 1.3 0.2 7.4 Treatment Mineral oil: 30-minute emollient exposure eliminated C O N S C - C/C - O A 82.3 12.5 2.8 N.D. 9.7 B 75.8 14.8 6.3 1.8 5.4 C 78.7 12.8 4.7 1.4 6.4 solution immediately after the mineral oil was rubbed onto the skin surface. In this case, a loss of performance versus the standard treatment conditions is observed. CONCLUSIONS As in similar studies on hair substrates, ESCA has proven to be a valuable technique for determining the adsorption of various polymers on stratum corneum membranes. In addition to its inherent surface sensitivity, ESCA provides some distinct advantages, including the use of a small amount of sample, rapid analysis, and the ability to provide semiquantitative measurements of polymer-surface coverages. The technique is appli- cable to any topical agent possessing suitable elements or functional groups which are specific to the agent under examination. Specific facts emerging from this study in- clude: A) Polyquaternium-24 adsorbs more strongly to skin membranes than Polyquater- nium-10 or chitosan. B) In contrast to Polyquaternium-24, which shows roughly equivalent deposition on both sides of the membrane, Polyquaternium-10 and chitosan provide deposition only on the inner surface of unwashed skin membranes. This is attributed to the presence of retained lipids on the outer surface during contact with the aqueous polymer solutions. C) Following removal of native lipid on the stratum corneum by washing in SDS, the polymers exhibit equivalent deposition on the inner and outer surfaces. Polyquater- nium-24 achieves the highest absolute level of adsorption. D) Topical application of lanolin in a set of five emollients provided the greatest degree of protection from the effects of SDS washing. ACKNOWLEDGEMENTS The capable experimental assistance of E. Lesniak and D. G. Weternik (skin treat- ments) and D. H. Scofield (ESCA) is gratefully acknowledged. The experimental

306 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS polymers used in this study were supplied by G. L. Brode. Tom Kinisky is also ac- knowledged for his work in performing the preliminary ESCA experiments which dem- onstrated the feasibility of this study. REFERENCES (1) D. T. Clark, "The Investigation of Polymer Surfaces by Means of ESCA," in Polymer Surfaces, Clark and Feast, Eds. (John Wiley & Sons, New York, 1978), pp. 309-352. (2) A. Dilks, Polymer surfaces, Anal. Chem., 53, 802A-816A (1981). (3) M. K. Bahl, ESCA studies on skin lipid removal by solvents and surfactants, J. Soc. Cosmet. Chem., 36, 287-296 (1985). (4) J. A. Faucher and E. D. Goddard, Sorption of a cationic polymer by stratum corneum, J. Soc. Cosmet. Chem., 27, 543-553 (1976). (5) E. D. Goddard and W. C. Harris, An ESCA study of the substantivity of conditioning polymers on hair substrates, J. Soc. Cosmet. Chem., submitted for publication. (6) J. A. Faucher, E. D. Goddard, R. B. Hannah, and A.M. Kligman, Protection of the skin by a cationic cellulosic polymer, Cosmet. Toil., 92, 39-44 (1977).