272 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) J. Dubourg and P. Devillers, Contribution it l'6tude de la r•action de Maillard, Bull. Soc. Chim. Fr., 116, 117, 603-608 (1962). L. C. Maillard, Action des amino-acides sur les sucres. Formation des m61anoYdines par voie m•th- odique, C.R. Acad. Sci., 154, 66-68 (1912). J. Butcher, F. Bandelin, and N. Kanas, The reaction of D.H.A. with proteins, Amer. Perf. and Aromat., 75,(12), 46-48 (1960). K. Laden, and R. Zielinski, The reaction of hydroxymethylketones with skin and amino-acids, J. Soc. Cosmet. Chem, 16, 777-782 (1965). E. Wittgenstein and H. K. Berry, Reaction of D.H.A. with human skin callus and amino-com- pounds, J. Invest. Dermatol., 36, 283-286 (1961). B. Lustig, B. Katchen, and F. Reiss, The amino acid composition of the horny layer of the human skin, J. Invest. Dermatol., 30, 159-163 (March 1958). J. Morelle, Biochimie Cutan•e et lipoaminoacides de synthase, Vame colloque de Dermochimie, Collage de France 1966, Arch. Biochim. Cosmetol., lare partie, 95, 11-28 (March 1967), 2ame partie, 96, 11-32 (April 1967). R. Brun, A propos de la D.H.A., Parfum. Cosmet. Savons Fr., 6, 139-141 (April 1963). J. Cotte, F. Millet, A. Bernard, and M. C. Martini, Contribution • l'l•tude Expgrimentale du Pouvior Bronzant de la D.H.A. Compte rendu du deuxiame congras de Dermopharmacie, St Jacques de Compostelle, 1974, pp 177-187. N. Kanas, J. Butcher, and F. J. Bandelin, Factors influencing the tanning effect of D.H.A. on the skin, Amer. Perf., 75, 33-44 (November 1960). H. I. Maibach, and A.M. Kligman, Dihydroxyacetone: "a suntan stimulating agent," Arch. Der- matol., 82, 505-507 (April 1960). A. Meybeck, A spectroscopic study of the reaction products of D.H.A. with amino acids, J. Soc. Cosmet. Chem., 28, 25-35 (January 1977). M. F. Bobin, Etude de la Formulation et de la Stabilitg de la Dihydroxyacetone dans une t•mulsion, Thase Doctorat as Sciences Pharmaceutiques, n ø 193 (Lyon, 1982). H. W. Spier and G. Pascher, Quantitative untersuchungen iiber die freien aminosaiiren der Hautober- fli/che zur frage ihrer genesis., Klin. Wschr., 13, 319 (1953). Patent JA 127 999, 29.12.70, Nippon Kayaku Co. Ltd., Enrichment of soybean milk and artificial soybean protein meat by addition of methionine sulfoxide. Rapport I.F.R.E.B.R. 909 322, S.O.M. S, Tests de tolgrance locale, oculaire et itgrative. Test de sensibilisation cutange. Test de photoxicitg et de photoallergie, IFT-Hazelton, Les Oncins, B.P. 9, 69210 St. Germain Sur l'Arbresle, France. Rapport I.F.R.E.B. 8.11.106 L.C. 151 Test d'Ames. Patent Fr n ø 2 466 462 et n ø 2 491 080, Patent Brit n ø 2 062 016, Patent U.S. n ø 4 293 543, J.M. Cotte, Ph. Potin, Procgdg et composition pour la coloration de substances renfermant de la kgratine.

j. Soc. Cosmet. Chem., 35, 273-281 (August 1984) Quantitation of dimethicone in lotions using Fourier transform infrared spectral subtraction MARIE SABO, JOHN GROSS, and IRA E. ROSENBERG, Clairol Incorporated, 2 Blachley Road, Stamford, CT 06922. Received December 27, 1983. Synopsis A procedure for the quantitation of dimethicone in cream and lotion formulations has been developed. The procedure involves a solvent extraction and separation prior to analysis via Fourier transform infrared spectroscopy (FTIR). The samples are quantitated by comparison to a USP reference standard. The results show a slight positive bias due to matrix interferences however, a possible means of eliminating the bias is presented. The method is precise sample analyses gave a relative standard deviation of 1.78%. INTRODUCTION The quantitation of active ingredients in cosmetic and hair care products frequently proves to be quite challenging to analytical chemists. Often the active ingredients are present in low concentrations and the formulations have complex compositions. A typical lotion formulation might contain ingredients such as water, glycerin, stearic acid, mineral oil, acetylated lanolin alcohol, triethanolamine, cetyl alcohol, and car- bomer 934, and be preserved with DMDM hydantoin or methyl and propylparaben. The availability of high sensitivity instruments combined with computer-assisted data handling and raw data storage capabilities has, however, simplified the challenges. A case in point involves the quantitation of dimethicone present at the level of ca. 1% w/w in cream and lotion prototype formulations. Dimethicone (polydimethylsiloxane), a skin protecting agent (1), known for its water- repellant and anti-foaming properties, is the active ingredient in these products. It may be present in the formulations in the amount of 1 to 30% by weight. A literature search found few references (2-6) with quantitation procedures and, unfortunately, none of them directly yielded satisfactory results for these formulations. A modification of the United States Pharmacopeia (USPXX/NFXV) procedure was developed and val- idated. The method involves a solvent extraction and separation prior to analysis via Fourier transform infrared spectroscopy (FTIR). EXPERIMENTAL REAGENTS AND SOLUTIONS A dimethicone standard stock solution was prepared by diluting a 500-rag ampoule of 273